Religion is for the weak.

It gives people something to believe and put faith in, hoping that there is something better than reality. In all honesty, it works. Like you said, people 'converting' or just practicing a good Christian lifestyle can better their lives. I've seen it happen. Just think of all the ex-cons that come out of prison reformed, preaching, and end up turning their life around.

I don't really think their can be a definite answer to your question. If there weren't any religions in this world, what/who would people look to? There are natural instincts in humans to be leaders/followers, and if there weren't any religions in this world, you'd probably have a high number of sects and/or cults that believe in a common goal.

There will always be a greater power out there..