It's pointless. Very few people will be convinced by arguments. Refuting someone's entire belief system will not lead them to reevaluate their lives and follow us as though we were Jesus. This just doesn't happen.

The reason for this is people believe things without actually thinking about them. People manage to believe in things that are mutually exclusive. Debating them will just make them hate you for your air of superiority.

Discourse is useful for validating one's own beliefs. Throw ideas out there and if others can't refute them then they are probably good ideas. I don't think there is any other use.