I think the atheists in this board have been exposed to an especially obnoxious brand of christian. I apoligize for that - it is possible to be a christian and not feel the need to draw wandering generalizations about the life of others.
Technically, the doctrine is that a soul, and therefore conscience is from God. But, part of being human is that we have free will, and get to make our own decisions. But to say that “only a christian can do good” is implying not only that non-christians do only bad, but that a christian can’t do bad. Obviously, that’s just stupid. I consider myself a christian, and I do crappy stuff all the time. That’s what being a human being is all about.
As far as what faith you intend to follow, it is your choice. All faiths believe that their way is the way to salvation. Please, however, don’t write christianity off as a concept because of the nutjobs you have been exposed to. Besides, you know that there are “fundies” of all faiths - people so ademant in whatever they believe in - including atheism - you want to back off with your hands up and say "Whoa. Are you listening to you? " But, hey. Without the extremes, there would be no middle, right?