When you’re locked in vigorous discussion with someone on the topic of religion or related subjects, I find the temptation is to try and present counter-arguments which describe what you think is correct. However, I don’t think this is the easiest or most effective way to do it. In most arguments, it seems the easiest way to win, and by win I mean give the impression of superior reasoning, but not necessarily providing it for you’re own arguments, is to continually ask the other person questions.
This seems to make sense for two main reasons. Firstly, asking questions is a lot quicker than explaining reasoning, so while the other person is speaking and trying to justify a claim, you can think of the most cutting question possible and ask it in a few seconds. This gives them no time to think and they’ll probably give a less coherent answer because of it. (Though obviously it’s better for everyone involved to give the best responses they can, otherwise you’re not really discussing the subject properly and it just becomes a fight for the condescending high-ground. So you can just give them plenty of time to respond, and not rush the argument and hopefully they’ll give the response they wanted to.) Secondly, and more importantly, if you’re arguing on the subject of religion against a strongly religious person, it should be very easy to trace their arguments back to some inconsistencies, all you have to do is get them to explain them, and they’ll effectively argue against themselves.
This is where I return to the title of this post. The two most useful questions when debating in this manner seem to be “Why?” and “How do you know?”.
Though there is, unfortunately, that the other person will try to use this sort of method against you in discussions. I think the best counter-method is to be thoroughly intellectually truthful and to remember that not knowing is always an acceptable response.