The bottom line for me is that you can rarely get a religious person to discuss anything rationally, that is the point, they have dismissed rational argument and replaced it with the opposite.

I lived in Western Australia for over 20 years and as the weather is very kind in the Perth area where I lived, we had many couples knocking on the door selling their brand of religion.
I would say "You are the third couple to come knocking on my door, the others believe they are right, why are you right and they are wrong?"
They generally gave up at that point and went on their way.
I had not said I was an atheist, just that I could not make out the difference between the sects; perhaps that is what confused them?
I notice also that atheists rarely get angry when discussing theism but the theists get very animated, perhaps they protest too much?

Cheers,
Colin