IAmSinistar: I realise there are some folks who are so invested in delusion that I cannot dissuade them, but I can do my part to keep others from swelling their ranks.
This is exactly the reason why I can't stop discussing these subjects. I don't delude myself to thinking I can convince those that are vocal about their beliefs - most often those you actively take part in the dispute. These people are for the most part are too deeply rooted in their..., let's say, faith, and too apt at quelling the cognitive dissonance.
But there are those people who are wavering, insecure, curious or dissatisfied and doubting. Helping them making a "more informed" choice about their take on life/belief is one of my aims.
The other one is just plain selfish cantankerousness ;-), or just the fun of dispute.