To be blunt, I think you're asking stupid questions and putting them to the wrong people. Imagine going into a conservative forum, like this one, and asking "but what if liberalism really is true? Gosh, then what? What if the Marxists are right? What if the 9/11 attacks were justified?? Then what?" It comes off as stupid and offensive, just like your "what if muslims are right?" questions. Muslims are not right. Muslim beliefs are not right. Blowing up America is not right. You know this. So stop it.
Now, about the 2.1 degrees. Here is how it started. Read this extraordinary thread. The fun begins with comment 482.
Again, it was strictly in the context of Pascal's Wager, and was simply used to illustrate the weakness of it. If it makes you more comfortable, feel free to replace Islam with Buddhism, Zoroastrianism, Shinto, etc.; the point still stands.