We are making a leap of faith anytime we do something, regardless of religion. We do everything based on our previous experiences with similar situations. When we take a step we trust ourselves that because we didn't hurt ourselves the previous millions of time we won't do it now either.

What religion does is (excluding many other humanitarian activities) it gives a moral background to believers based on the Catholic Church's point of view or less optionally on the Bible, or other holy books/teachings (but as an earlier commenter said the previous is NOT based on the Bible, it did evolve/improved simultaneously with humanity). Religious people then, depending on their level of faith, incorporate it into their own moral belief system, the same way as atheist do, just instead of the Church's, based on some other source, institution, books, stories, movies, etc (but religious people also build from these). There is almost no difference between two such people. Also, I don't know about any main religion that would have teachings that largely conflicts with western ideology's, and even if they do, religious people HAVE an option to ignore or follow those. Problems can arise (I by no means try to say that religion is perfect, but for some reason people tend to think that atheists and believers are so different) when for example the families push their own way of thinking too hard on their children, who in exchange will pass it onto their own, but it's a problem with atheist's families as well (also probably slightly smaller)

About the problem you mentioned as man in the middle attack stems from some (overly small percentage) people who lost their contact with reality, and as far as I know that is just the definition of schizophrenia. As for whether there is a correlation between religiosity and schizophrenia, I couldn't find any concrete study with numbers, but I doubt it would be significant.