The only belief system that must be right is that held by atheists.
It’s the only logical conclusion to draw from the available evidence: they are among the most vocal, most argumentative, most defensive, most worried group of people on the planet.
If I, a Christian, am wrong about the existence God, what have I lost? Time on Sundays, time reading the Bible, time trying to convert my friends… but only time. If a Muslim is wrong about the existence of Allah all he has lost is time. If the Jew, Hindu, animist, Mormon, etc are all wrong about the existence of any god they’ve only wasted time.
But if an atheist is wrong about the non-existence of any God, he’s in for a heap of hurt: eternal damnation, Hell, reincarnation as a rat, etc.
For the sake of the atheists in the world, I could pray there is no God. Of course, I don’t know who I’d pray to. But for the sake of those who believe there is no God – of any kind – I could hope they’re right, and that I’ve just been wasting thousands of hours of my life I could better spend on me.
I am convinced there is a God, though, so the only logical course of action I can take is to try convince others. After all, if I’m wrong, I just spent a bunch of time doing something that doesn’t matter.
But if I’m right…