See, that's exactly it. It is an open forum but there's a reason why it's not a free-for-all forum where different topics are discussed all in the same thread like a giant soup where anyone can discuss anything. If a topic is specific and not open ended then it should remain as such. Let me expand a bit so you can see (not necessarily agree) with my point of view.
Snakeface's topic and subject matter all dealt with the resurrection of Christ. Who did in fact resurrect him. If you look at his title and opening discussion NOWHERE does he ask or even hint at whether God exists or not. The topic at hand is Who Resurrected Jesus. Had he asked if posters still believed in God or if science could explain his resurrection then I'd agree with the commentary on God's existence. Snakeface would have left this open for debate had he made these remarks.
Imagine you opened a thread talking about SUV's and the different makes, models, features, and capabilities. Then I come along and start talking about the modifications I recently made on my four door sports sedan? I could easily argue that both are considered cars and therefore, I should be able to join your conversation. But, you see the difference? Yes, snakeface was talking about God but he was being specific and was asking specifically. It wasn't a general discussion about God/Vehicles it was a specific request for further input about his resurrection/SUV's.