I remember during my undergraduate degree, having only recently become a Christian, a friend of mine telling me if I took a philosophy course, I would be convinced there was no God. I never did take that philosophy course (although I have read widely in philosophy), but not out of fear of losing faith.
There are Christians who are suspicious of philosophy and who possibly fear philosophy as a faith-killer. I came across this quote by one of the church fathers, Clement of Alexandria (150-215 AD), that I think is very helpful:
But the multitude are frightened at the Hellenic philosophy, as children are at masks, being afraid lest it lead them astray. But if the faith (for I cannot call it knowledge) which they possess be such as to be dissolved by plausible speech, let it by all means dissolved, and let them confess that they will not retain the truth. For truth is immoveable; but false opinion dissolves. (Stromata 6.10)
Truth is truth and no philosophy can change that. Study that is aimed at the truth will only reveal what is within us that is not true. For Christians, this may change some of their Sunday school faith, but it should lead to a solid and rational faith in Christ.