The best logical explanation I have seen was a letter in New Scientist by someone who said they just can’t believe in any entity that doesn’t have to obey the laws of physics.
I think what did it for me as a kid was the concept that you get reunited with all of your family in Heaven. I really wasn’t happy with that idea. Going to churches just reinforced the problem when they said anyone could get into Heaven if they believed hard enough and confessed their sins. I really don’t want to spend eternity with most of the people I’ve met.
“Making it up?! Why would I be making it up? Life is horrible enough without making any more of it.” -Marvin the Paranoid Android