Keller begins his transition from Part 1 to Part 2. After highlighting some of the unproven assumptions behind the objections against Christianity, he now wants to outline the baseline assumptions that play into the argument he will make for Christianity.

Since Christianity is a diverse religion with hundreds of individual denominations, Keller specifies that he has in view not one small slice of Christianity (such as his own Presbyterian denomination), but rather the broad and unified stream of agreed-upon doctrine from the earliest centuries of the faith: “[A]ll Orthodox, Catholic, and Protestant Christians assent together to the great creeds of the first thousand years of church history […] For our purposes, I’ll define Christianity as the body of believers who assent to these great ecumenical creeds” (121). As such, Keller’s arguments for Christianity will focus on the broad themes of God’s existence and on the person and work of Jesus Christ as portrayed in the historical gospels.

Keller also reviews some of the philosophical models for seeking knowledge, arguing that many of the critics of Christianity are depending on a particular model—strong rationalism—which has long been avoided by philosophers: “[Strong rationalism’s] proponents laid down what was called the ‘verification principle,’ namely, that no one should believe a proposition unless it can be proved rationally by logic or empirically by sense experience” (122).