My problem with comparing God with Santa Claus or the invisible pink unicorn or whatever is that you can't. Santa Claus isn't a concept that mankind has believe in, to some degree or another, for thousands upon thousands of years. The invisible pink unicorn isn't something that gives people solace and hope and helps them through their lives. People do not live or die for or devote their lives to the flying spaghetti monster. God, or whatever you want to call it, is not the same as just another old imaginary being or person.
So people putting stock in something makes it more likely to be true? I would have to disagree very strongly with that notion.
When nearly all people of all cultures and ethnic groups of all eras of human civilization put stock in it, then it's not necessarily true, no, but not something you can dismiss as easily as Santa Claus.