What were the boundaries of the Christian faith? How is heresy discerned? Blomberg surveys the New Testament to ascertain what was deemed orthodox.

Many divisions between church denominations can be traced back to differences in four doctrines: sola scriptura, freewill, the relationship between the Old and New covenant, and the sacraments. In this article, focus is given to the doctrine of sola scriptura as the only rule of faith. Here the Catholic, Orthodox, Mormon and Pentecostal positions on sola scriptura are evaluated in light of the Protestant view.

Throughout the history of the church, heretics often protested against orthodox confessions on the ground of the so-called "non-scriptural language" of the orthodox creed. They pointed out that phrases such as “of one essence with the Father,” and “one substance with the Father” were not to be found in Scripture. Heretics often used the argument “no creed but the Bible” precisely so that they could use biblical language to evade biblical truth.