Theists: What is the most compelling argument you have heard for Atheism?

[Fake Messiah]

Regarding the arguments as a group, they are inductive in nature and give a probabilistic conclusion.  I think very few people become a Christian because of the arguments--rather it is an assurance that a belief in God (at least a god) is not irrational and serves as a check against the barrage of atheists shallow challenges to faith being a reasonable thing to hold.

Well if they are such shallow challenges why do you fail so miserably to answer them? For instance you claim "God is the best explanation why anything at all exists." and yet there is no answer to why dysentery, malaria, AIDS, cancer, earthquakes exists. Or at least you don't know them.
This is just one of many unshakable problems for Theism and you simply ignoring them makes you that much delusional.