Discipleship is a term that refers to the totality of practices in the Christian life. It is the ongoing status of being a disciple of Jesus Christ—i.e., a student of his teaching, committed to following his ways. It includes a sense of continued growth and intentional activity—it is not simply a term for a passive state of identity. This is Platt’s preferred terminology for what it means to be a Christian, and he uses it in several different forms, especially when referring to evangelism, where he speaks often of “making disciples.”

Evangelicalism is a specific subset within the broader landscape of global Christianity notable for its focus on spreading the teachings of Jesus throughout the world. Evangelicals place particular importance on personal conversion—framed as the transformative experience of being “born again” as a Christian—and hold that the Bible is the infallible word of God and the ultimate authority for Christian living. A wide variety of Christian denominations, both Catholic and Protestant, fall under the wider banner of evangelicalism.

In Platt’s explanation of the Christian mandate toward the world, he frequently phrases it as consisting of two elements: first, of multiplying—that is, of spreading the gospel and making disciples—and second, of making God’s glory known to the ends of the earth. Glory, in this context, refers both to the sovereign majesty of God’s presence and character and also to the worship that is due him. Highlighting God’s glory as one of the core pieces of the global Christian mission has significant biblical grounding, and it is especially common in the works of Reformed evangelicals like Platt (those who follow a Calvinist-inspired theology, focusing on the sovereignty of God in all things).

“Gospel” is the English translation of the New Testament‘s Greek word evangelion, which means “good news.” It is a common word in Christian thought and literature, and it can be used in two different ways. It refers either to (1) the general Christian message about the salvation God has provided through Jesus Christ, or (2) one of the four texts in the New Testament that serve as accounts of Jesus’s life and ministry. In the first instance, the word is usually uncapitalized (e.g., “to proclaim the gospel of Jesus Christ”), while in the second instance it is capitalized (“the Gospel of John“).

This is Platt’s term of choice when referring to a healthy church. Part of his challenge in Radical is for people to connect to a church if they aren’t already attending one, but he specifically refers to it as a “multiplying community.” Platt regards the mandate of making disciples as lying at the core of the Christian calling, and so a church is only really fulfilling its purpose if it is making the gospel known and multiplying its members. He advises his readers to seek out a multiplying community—especially one seeking to make disciples both in its local area as well as in other nations.