Christopher J. White is a good example of posting the more violent version:
His count down got down to the last couple of minutes when a Navy SEAL, just released from the Navy after serving in Afghanistan and Iraq and newly registered in the class, walked up to the Professor. The SEAL hit him full force in the face, and sent the Professor tumbling from his lofty platform. The Professor was out cold!! The students were stunned and shocked. They began to babble in confusion. The SEAL nonchalantly took his seat in the front row and sat silent. The class looked at him and fell silent...waiting.
Eventually, the professor came to and was noticeably shaken. He looked at the SEAL in the front row. When the professor regained his senses and could speak he asked: "What the hell is the matter with you? Why did you do that!?"
"God was really busy protecting America's soldiers, who are protecting your right to say stupid shit and act like an asshole!!! So he sent me!!"
Utterly Boring posts a slightly less violent version:
He got down to the last couple of minutes and a Marine just released from active duty and newly registered in the class walked up to the professor, hit him full force in the face, and sent him flying from the platform.
The professor struggled up, obviously shaken and yelled, "What's the matter with you? Why did you do that?"
The Marine replied, "God was busy; He sent me."
So, what are we to learn from this story? Apparently "proof" of God for an atheist legitimately includes physical force and violence. I don't think that I've ever seen a more literal expression of the argumentum ad baculum (Appeal to Force) fallacy. It's OK to assault an atheist who doesn't believe in your god. Indeed, it's OK to see yourself as the violent instrument of God's will — it's not really you who is assaulting the atheist, but God because God sent you.
I suppose there is no greater feeling than that of being an instrument of God, especially when it gives you the excuse of act out violent fantasies against those with the temerity to reject your religious faith. The atheist might have the right to say such things — a right protected by American soldiers — but that doesn't mean that they will be free from paying a price in blood and pain.
Come to think of it, though, I'm not so sure that I want my freedoms protected by a "soldier" who will just come home and start assaulting people he disagrees with in the name of his God. I think I'd rather be unprotected than rely on the "protection" of a sociopath like that.
This is nationalistic American Christianity. Notice that the violence is perpetuated by a member of the American military — ostensibly tasked with defending America, but here tasked by God with defending the True Faith. For the Christian Right, America and Christianity tend to be identical. This is also anti-atheist bigotry. A parallel story of violence towards a Jew or an Asian would be quickly condemned, but it's OK to post "humorous" tales of violence towards atheists because... well, because atheists just don't matter. They are unworthy of the same consideration and decency Christians have had to learn to show towards others.
Do you see any connection with biblical Christianity? Paul and other evangelists are frequently portrayed as debating others, but there aren't any records of them assaulting their opponents. Their weapons of faith and love; for American Christians, the weapons have become violence and terror. Faith and love are the tools used by people who are confident in themselves and their agenda; violence and terror are the tools used by people who are afraid.