Atheists, tell me, a Roman Catholic: why should I become an atheist?

[Mr Greene]

Don't worry, I'm going to stick around at least until I feel like I've made a genuine conclusion about the existence of God.

Currently I've been looking a little more into why Christians believe in God (I've seen some ideas about how God could be a manifestation of our own ego, for example) to gain some perspective before I look into the ontological/teleological/etc. arguments.

Perhaps it would be interesting to look at the origins of the gods themselves;
ie; the paintings of Lascaux and the Venus Figurines. 
Contemplate what they meant to the people who made and used them.