Presuppositional apologetics should emphasize the antithesis between the Christian and non-Christian worldviews. It seeks to point out the inconsistency and arbitrariness of both the unbeliever's worldview and how he lives his life in relation to his professed worldview. Likewise, the Christian cannot put forth a credible defense of the faith if either his words or his deeds undermine one another through inconsistency.

The Christian worldview can account for the presence of some sin in the life of a believer: "If we say that we have no sin, we are deceiving ourselves, and the truth is not in us" (1 John 1:8). However, the Christian faith does not allow for gross sinful conduct on the part of the believer: "No one who abides in Him sins; no one who sins has seen Him or knows Him. Little children, let no one deceive you; the one who practices righteousness is righteous, just as He is righteous; the one who practices sin is of the devil... " (1 John 3:6-8a).