What I love about this well-worn atheist ‘argument’ is that it actually serves to demonstrate how vastly different a belief in God is to these myths and imaginations. When one honestly assesses the Judeo-Christian doctrine of God he will find multiple thousands of years of human testimony and religious development; he will find martyrs enduring the most horrific trauma in defense of the faith; he will find accounts in religious texts with historical and geographical corroboration; etc (these fact are of course not ‘proofs,’ but rather ‘evidences’ that elicit strong consideration). Pit this against tales of the Tooth Fairy, Santa, and Spaghetti Monsters and one finds the exact opposite: no testimony or religious refinement, no martyrs, no historical and geographical corroboration, etc. Instead, one finds myths created intentionally for children, for point making, or for whatever. It’s strawman argumentation at its worst.
Again, just to be clear, testimony, martyrs, geography, etc., are not “proof” that God exists, but rather proof that comparing faith in God to faith in fairies and Santa is totally different.