The Protestant Reformation of the sixteenth century—the beginnings of which are usually associated with the work of Martin Luther (1483–1546)—was really a collection of reformations across Europe. Various reformations of the church, theology, public worship, and even the broader society took place in nations including Germany, Switzerland, the Netherlands, Scotland, and England. Originally intended to reform the Western church from within, the Reformation led to a self-conscious effort to abandon the trappings of Roman Catholicism so that a true church might continue, since the Roman Catholic church had rejected vital theological reforms. Today, the theological principles of the Reformation may be summarized by the five solas—namely, that sinners are saved by grace alone, through faith alone, in Christ alone, under the authority of God’s Word alone, and all to the glory of God alone.

The Puritans of the sixteenth and seventeenth centuries sought to bring about a more thorough Reformation in England—to purify the English church from any Roman Catholic vestiges—especially in the areas of theology, worship, and personal holiness. Originally used pejoratively, the term Puritan referred to one who, politically, reacted against the via media (middle way) of the Elizabethan Settlement; who, theologically, held the Reformed views of the five solas and (usually) the doctrines of grace summarized by the acronym TULIP; and who was committed to discipleship, evangelism, an experiential faith, communion with God, and personal piety. Despite their commonalities, there was no unified Puritan view on topics such as church government and baptism. While there has been much debate over the exact dates of the Puritan movement, Puritanism flourished between 1558 and 1689 in England and during the early eighteenth century in America.

No one who trusts in Jesus Christ will be eternally lost. Jesus said, “All that the Father gives to me will come to me, and whoever comes to me I will never cast out” (John 6:37). Anyone who has come to Christ belongs to Christ forever. Everyone who has faith in Christ has eternal life (John 6:40).

Yet Christians often fear that they have not really come to Christ. They want assurance that their faith is real. They want to know for sure that they are God’s children. The Bible teaches that this desire for assurance conforms to God’s will for His people. God wants believers to know that their faith is genuine. He wants them to be sure that they belong to Him and have eternal life through Christ.

Gender-neutral language in the field of Bible translation refers to grammatically masculine words in the original languages of Scripture being rendered with non-gender-specific glosses in English translations. In some cases, this is a result of differences between modern English and the biblical languages, and certain gender-neutral glosses provide a legitimate translation of Hebrew and Greek nouns and pronouns when they represent both males and females. As a result, some amount of gender neutrality is employed by every English translation of Scripture. In other cases, however, translators have used gender-neutral language in such a way that it erodes the integrity of the resulting translation.

The question of gender-neutral language became controversial in the late twentieth and early twenty-first centuries as translators and publishers sought to adapt their translation of nouns and pronouns to contemporary changes in the English language. This resulted in the gender-neutral controversy, a debate among evangelical and Reformed theologians over Bible translation theory and philosophy. In the 1990s, certain translators produced intentionally gender-neutral translations, purposefully introducing egalitarian agendas into their translation of masculine nouns and pronouns. One of the more controversial Bible translations was the 1996 New International Version Inclusive Language Edition (NIVI). The gender-neutral controversy manifested itself in evangelical circles on account of debates over gender wars between egalitarians and complementarians. This debate also exposed disagreements among complementarians over historical understandings of the Trinity.

In the Gospels, Jesus called those who believed His teachings disciples (Matt. 9:14; 16:24; Mark 2:16). After His resurrection, He gave these believers a mission: “All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you” (Matt. 28:18–20).

Jesus made disciples. Then, as He prepared to return to heaven, He told these disciples to “make disciples.” But what are disciples? And how does Jesus say they are made?

The medieval church period spanned roughly one thousand years (AD 500–1500) and produced several figures and ideas that continue to influence the church today. This era—the name of which is derived from the Latin phrase medium aevum (middle age)—began with the fall of the Western Roman Empire and ended roughly with the beginning of the Renaissance and the Protestant Reformation. During the medieval era of church history, the power of the papacy grew, and the biblical gospel was slowly eclipsed, although several individual thinkers made important contributions to our theological understanding. The full-orbed truth of the gospel would not be restored to a prominent place in the church until the Protestant Reformation. Nevertheless, God preserved His remnant throughout the medieval church period.

Baptism is a sacrament sovereignly instituted by God to be a sign and seal of the new covenant. Through a symbolic washing with water, the Lord signifies and seals the covenant promises to forgive, cleanse, and renew His covenant people. The meaning of baptism is rooted in the meaning of the covenant signs in the Old Testament. In the new covenant, baptism has replaced the old covenant sign of circumcision. Both sacraments signified membership in the visible church. Both point to the promise of redemption through the shed blood of Jesus. As a preparatory sign in redemptive history, circumcision was a bloody rite that pointed to the death of the Savior. After Christ shed His blood at Calvary, there was need for a new sign of initiation into the new Israel. Accordingly, Christ instituted the sign of baptism to be the unbloody sign of the new covenant. The proper recipients of baptism are all who profess faith in Christ, together with their children.

During the eighteenth century, the Enlightenment, the First Great Awakening, revolutions in both America and in Europe, missionary expansion, and musical development all left their mark on the church. The principles and ideals forged in the furnace of the religious and societal upheaval brought about by the Renaissance, the Protestant Reformation, and the colonization of the New World during the sixteenth and seventeenth centuries continued to reverberate. Many significant events and people reshaped the church, with effects lasting to the present day.

The Lordship Controversy occurred in the last two decades of the twentieth century. It was a debate largely between dispensational theologians regarding the nature of salvation and the place of repentance in the life of true believers. On one side of the Lordship Controversy was a company of “Free Grace” theologians who denied that repentance and obedience are necessary in the Christian life. On the other side of the controversy was a group of Calvinistic theologians who taught that although salvation is based only on God’s sovereign grace, God requires the evangelical response of repentance and faith in our reception of the gospel. The latter emphasized the importance of the lordship of Christ in reaction to the denial of the need for repentance and the fruit of obedience in the teaching of the proponents of the Free Grace movement. By undermining the place of repentance and good works in the life of a believer, proponents of the Free Grace movement essentially advanced an antinomian view of justification. Although there was enough uniformity on each side of the debate to label these two different positions, there were also nuances in the way in which individual figures articulated the dynamics of both the Free Grace and the Lordship Salvation approach to the doctrine of salvation.

The word joy appears nearly two hundred times throughout Scripture. The Old Testament is filled with references to joy, from the psalmist who “shout[s] to God with loud songs of joy” to the prophet Isaiah describing “everlasting joy” (Ps. 47:1; Isa. 35:10). When we come to the New Testament, the Apostle Paul reminds believers that joy is a fruit of the Holy Spirit, a virtue present within Christian believers (Gal. 5:22). Joy is not to be confused with happiness, which is often based on favorable circumstances. True abiding joy is a feeling within believers of inner gladness, delight, or rejoicing despite circumstances.

Fasting means to abstain from eating and/or drinking as an act of personal and corporate piety. It is common in religions around the world, but in the Christian faith, it holds special significance and can be seen throughout Scripture. During His earthly life, Jesus corrected and clarified the purpose and role of fasting (Matt. 5:16–18; 9:14–16).

Scripture has much to say about strength. The prophet Isaiah called out, “The Lord God is my strength and my song” (Isa. 12:2). Jesus commands His followers to love God “with all your soul and with all your mind and with all your strength” (Mark. 12:30). Paul alludes to the fact that we are strengthened by spiritual gifts (Rom. 1:11). Paul confirmed to young Timothy that he was strengthened by the Lord for the preaching of the truth (2 Tim. 4:17). Perhaps one of the most well-known passages about strength is Philippians 4:13: “I can do all things through him who strengthens me.” According to all these passages, the origin of our strength is God. The psalmist wrote, “Be strong, and let your heart take courage, all you who wait for the Lord” (Ps. 31:24). Isaiah said that the Lord “gives power to the faint, and to him who has no might he increases strength” (Isa. 40:29).

Dispensationalism is a modern hermeneutical system of theology that exists as an alternative to historic Reformed covenant theology. Dispensationalism originated in the nineteenth century in the writings of John Nelson Darby. It has spread rapidly throughout the church in the Western world since in the second half of the nineteenth century. So widespread was its reception that the majority of evangelicals in the United States and Britain came to embrace some elements of it. The flourishing of dispensationalism in the twentieth century was due largely to the advent of “prophecy conferences,” the widespread use of the Scofield Study Bible, and the establishment of dispensational Bible institutes and colleges. There are three distinct characteristics of dispensationalism: a sharp distinction between Israel and the church, the division of the history of salvation into dispensations, and a woodenly literal hermeneutic regarding biblical prophecy and apocalyptic literature. At the end of the twentieth century, refinements made to classical dispensationalism resulted in the propagation of progressive dispensationalism, which makes many of the traditional dispensational distinctions but also sees greater continuity overall between the various dispensations and between old covenant Israel and the new covenant church.

The New Perspective on Paul is a theological movement that achieved widespread popularity in the first decade of the twenty-first century. While the viewpoints among New Perspective proponents are not monolithic, all generally insist that the teaching of second temple Judaism should be the guiding standard for understanding the background of Pauline theology. New Perspective adherents also generally believe that historic Protestantism has fundamentally misread the Apostle Paul by reading Reformation-era debates back into his works. Consequently, theologians of the New Perspective have recast the Reformed understanding of justification and the gospel. Some New Perspective scholars have offered readings of Paul that are not substantially different from interpretations of Paul proposed by Roman Catholic theologians during the Reformation. Many New Perspective thinkers have asserted that “the gospel” is not the message about how an individual is saved; rather, it is has to do with how one identifies the members of the new covenant community. These theologians radically redefined the Protestant and Reformed doctrine of justification by faith alone. Many Reformed theologians offered strong and nuanced critiques of the New Perspective throughout the first two decades of the twenty-first century.

Creationism teaches that the eternal, self-existent God created the universe, and this doctrine is attested to throughout the Old and New Testaments as a foundation of the faith. It stands as the first doctrine revealed in Scripture. The doctrine of creation makes a sharp distinction between the Creator and the creature. The triune God has revealed Himself to be the Creator of the heavens and the earth. God reveals His attributes in the creation of the universe. With the advent of the evolutionary theory of origins, creationism became a controversial doctrine. The materialistic and naturalistic worldview of evolution stands in stark opposition to the biblical doctrine of creation. Modern secular scientific theories in astronomy, biology, and geology have attempted to bolster a naturalistic worldview.

Although Christians have agreed that God created ex nihilo, “out of nothing,” there has been some disagreement on issues such as the age of the earth and what the six days of creation in Genesis 1 signify. One of the most widely held positions is that Genesis 1 teaches that God created everything in six ordinary twenty-four-hour days. Since the advent of scientific theories of origin and material aging, more proposals have been raised. Today, we can make a distinction between young-earth creationism and old-earth creationism. Young-earth creationists hold that the created order is relatively young, perhaps no more than about ten thousand years old. Old-earth creationists believe that the universe is much older, being millions or even billions of years old.

The ancient church or early church period—stretching from the beginning of the New Testament church to the beginning of the Middle Ages (c. AD 600)—was characterized bloody persecution, the spread of the gospel throughout the Roman Empire and beyond, and the theological codification of the doctrines of the Trinity and of the person and natures of Christ. The New Testament church was born through the life, death, and resurrection of Jesus and His subsequent pouring out of the Holy Spirit on His disciples, who then proclaimed that all people can be saved by grace alone through faith alone in Christ alone. The new covenant church was not entirely new, for it was established in creation and preserved after the fall through the covenant that God made with Abraham in Genesis 12. Thus, the new covenant church is a continuation of the old covenant community, though under the new covenant, God’s people have a greater understanding of the fulfillment of the messianic promises and a fuller experience of the Holy Spirit than those who lived before the coming of Jesus. The earliest Christians devoted themselves to the Apostolic teaching, to the breaking of bread, and to prayers, and “the Lord added to their number day by day those who were being saved” (Acts 2:47). Against the backdrop of heresies and a series of ecclesiastical councils, the ancient church developed doctrinal confessions of faith—the ecumenical creeds—that are still used around the world today.

A defining characteristic of the Holy Spirit’s work in a believer’s life is the virtue of humility. Humility is the antithesis of pride and manifests itself most fully when we examine ourselves in light of our sinfulness and God’s perfect holiness. Scripture is clear that a truly humble person has a correct view of himself (Rom. 12:3), denies himself and places others’ needs first (Phil. 2:3), exhibits grace and love toward others (Eph. 4:32), and points to Christ (1 Cor. 10:31). Ultimately, a humble person follows the example of the Lord Jesus Christ, who is our preeminent example of genuine humility.

The twenty-first century witnessed dramatic shifts in both individual and cultural expressions of faith. In the United States, the proportion of those who identified as Christians decreased from 82 percent of Americans in 2001 to 63 percent by 2021. In addition, various lifestyle and moral reflections of faith saw a dramatic shift. Views of family, gender, and work increasingly departed from a biblical worldview in favor of secular, nonreligious perspectives. Notwithstanding these changes, various traditions saw a revival of interest and influence, including the prosperity gospel, megachurch evangelicalism, and Reformed Christianity, especially among younger generations. The twenty-first century also witnessed the proliferation of access to the internet and smartphones, which dramatically changed the cultural, economic, relational, and religious experience for billions of people around the world. In the milieu of heightened awareness of militant Islam (e.g., post-9/11) and societal changes due to a global pandemic (e.g., COVID-19), these changing cultural, religious, and worldview expressions led to what some are calling a revolution of faith and morals in the early part of the twenty-first century.

At the end of the nineteenth century, an intramural debate arose among Christians over which version of the English Bible should be used. This debate was occasioned by the discovery of numerous Greek manuscripts of the New Testament in the mid-nineteenth century and the subsequent translation and publication of new versions of the English Bible after 1880. Proponents of the King James Only movement insist that the King James Version (KJV) is the only legitimate English translation of Scripture and that none others are valid. Proponents of the King James Only movement have belonged to a variety of ecclesiastical fellowships. A distinction should be made between those who believe the King James Version is the only legitimate English translation of the Bible (the King James Only movement) and those who believe that the King James is to be preferred over other English Bible translations but that it is not inherently wrong to choose other English versions. Some churches and individuals, largely for historical and stylistic reasons, believe that the King James Version remains the best English translation of the Bible while not insisting that all other English versions are wholly illegitimate.

The Christian virtue of love is a fruit of the Holy Spirit (Gal. 5:22–23), and descriptions of it can be found throughout the Bible. Such love differentiates believers from all other people. However, love is not confined in the Bible to a mere expression of self-giving and self-sacrifice between one person and another. In Scripture, love is manifested in various spheres. Chief among these is God’s love, which is supremely expressed in Christ (Rom. 5:8), but we also see a believer’s love for God (Deut. 6:5), man’s love for his neighbor (Matt. 22:39), and man’s love for impersonal things (Titus 1:8; 1 Tim. 6:10; 2 Tim. 3:4).

One of three theological proposals regarding the salvation of unreached peoples, along with pluralism and exclusivism, inclusivism is the belief that God through Jesus Christ saves individuals who have never heard the gospel. It is distinct from pluralism in that it does not teach a universal salvation or the possibility of salvation apart from Christ for adherents of other world religions. It also stands in stark contrast to exclusivism, which teaches both that Jesus Christ is the only way of salvation and that all people must respond to the message of the gospel in faith and repentance to be saved. The primary arguments of inclusivists rest on their understanding of concepts such as general revelation and the conscience, the justice of God and eternal punishment, and sincere repentance and seeking. Historic Reformed theology is thoroughly exclusivist and explicitly opposed to all arguments advancing various forms of inclusivism.

Scripture describes two primary kinds of peace. The most tremendous peace that anyone can experience is the peace with God that occurs whenever someone is reconciled with Him through faith in Jesus Christ. This is the purpose for which Christ came into the world. Paul said, “In Christ God was reconciling the world to himself, not counting their trespasses against them” (2 Cor. 5:19). Once enemies of God because of our sin, sinners enjoy peace with God by and through the blood of the cross of Christ (Col. 1:20). This objective peace with God enables us to experience a subjective or inner peace before Him. The second kind of peace is found in the Beatitudes of Jesus when He labels all believers “peacemakers” (Matt. 5:9). Since God is a “God of peace,” it stands to reason that His children take on the same characteristic and become peacemakers (Rom. 16:20; 1 Thess. 5:23; Heb. 13:20).

There is nothing more foundational to knowing God than the His self-revelation to His creatures. Though He is incomprehensible, the true and living God reveals aspects of Himself in both creation and in Scripture. Theologians refer to these two ways of God’s self-revelation as general or natural revelation and special or supernatural revelation. In creation, God reveals aspects of His being, attributes, and power. In Scripture, He gives further revelation of His being, names, attributes, works, and will for the salvation of His people. All special revelation centers on the person and saving work of Jesus Christ. Jesus is Himself the full revelation of God to mankind. He is the eternal Logos who, in the fullness of time, entered the world He created to redeem a people for Himself. The Holy Spirit is both the divine agent of God’s special revelation as well as the One who illumines the hearts of believers to give them a saving understanding of that revelation.

The doctrine of the Trinity is foundational to the Christian faith and to Christian living, since knowing God is at the heart of biblical religion and God is fully revealed as Father, Son, and Holy Spirit in the unfolding of the divine mystery. The one true and living God eternally exists in three distinct yet inseparable persons. The creeds and confession of the church summarize the essential biblical truths about the triunity of God, providing theological nuance and support for this foundational doctrine. Nevertheless, the doctrine of the Trinity has also been frequently misunderstood, misrepresented and perverted. Considering biblical support for the doctrine of the Trinity and its historical development will help us more accurately comprehend this precious truth.