1. The point in a rational discussion or debate in which one side's argument is ultimately found to rely on one's belief in God or a particular dogmatic religious tenet. This is known as the God Wall, or the point where reason, logic, evidence, and empirical observations smash futilely against the ironclad stance of faith with little to no persuasive impact on the argument or position being discussed.
2. A protective shield or mental block used by religious believers to ward off any and all arguments used against their faith-based worldview.
"So why don't you think that Gay marriage is acceptable?"
"Because homosexuality is a sin, it’s not natural, and marriage should just be for heterosexual couples who want to start a family."
"But homosexuality occurs in most species, and scientists have shown us that its occurrence is a near universal phenomenon in nature. Further, mental health professionals have found that same sex couples make perfectly adequate parents and you don't have to be married to have a loving family. Why do you support discrimination against a minority group?"
"Oh, well, it’s God's law and He's all knowing and infallible. Plus, it’s in the Bible."
“Ahh, I seem to have backed you up against the God Wall in this conversation since my well reasoned arguments based in logic and evidence have had no impact on your stance."
"I'll pray for you, you heathen sinner."