Infallible in faith and practice

Once I dropped inerrancy I defaulted to a controversial position that holds that scripture is infallible in matters of faith and practice only. I thought to myself the Bible was given to tell the gospel story: it should only be considered authoritative insofar as what the Bible says deals with the gospel. This makes a lot of sense to me. But lately I've been having some doubts about this position; there is something about it that is deeply dissatisfying. Bibliology always has to be done, unfortunately, with one eye toward apologetics. If a non-inerrantist retreats to a position that says that the Bible is authoritative only in matters of faith and practice, that's like saying the Bible has been given to us by God, but it is only authoritative in those matters that are not empirically testable (matters of faith and practice). That seems to me like a BIG problem. I certainly would not accept such a position from any other religionist. I would think that they are only trying to save their religion at all costs by contriving their faith in such a way so that it is immune to criticism. What kind of faith is that? By parity of reasonning, why in the world should it be acceptable for a non-inerrantist to make such a move--deliberately exempting Christianity from all criticism? If I saw someone from another religion adjust his religious belief ad hoc in this way, I would certainly not be impressed. So the "infallible in faith and practice" position may have some serious problems associated with it that should be taken into consideration.