John Frame on Reason

There is no such thing as 'neutral' reasoning. There is only Christian-theistic reasoning and unbelieving reasoning: the wisdom of God and the wisdom of the world. When there is common ground between believer and unbeliever, that is a sign that either believer or unbeliever is inconsistent with his or her deepest commitments.
--John Frame, Five Views on Apologetics, p. 80, footnote 11


Further, agreements between believers and unbelievers indicate inconsistency in one or the other party. For example, when a Christian and an atheist agree on a scientific theory (assuming that the theory is true), the atheist is inconsistently relying on a worldview in which the universe is a rational order, matching the rational order of the human mind. At that point, the atheist is thinking as a theist. He is assuming a structure of rationality in the world that he has no right to assume.
--John Frame, Five Views on Apologetics, p. 136