Whenever someone is defending faith, or is arguing that faith and reason are compatible, they should be asked which of three common meanings of the term they are thinking of. If the exact meaning of the word isn't made clear, it is almost a given that their claims will deteriorate into a mess of equivocation.
When challenged to provide evidence for the existence of God, most theists reply that their belief is based on faith. This makes it clear that, in this context, “faith” means belief without evidence. This meaning of the word also applies to the claim that faith is needed when the evidence isn't conclusive. Or in other words, when the believer says that reason can only take one so far, and one must make the decision to believe.