There seems to be a point where a seemingly rational person becomes irrational when it comes to faith.
If you are broadly the same religion as your parents, or identify as a member of your national religion, it means you accepted what you were told by parents and peers.
Believing a man named Jesus, Mohammed, or whoever once existed is one thing, but basing your way of life on it and insisting your children do the same is madness if you boil it down. Just because something is old doesn't make it right.
All of our parents made mistakes, they were not perfect and all-knowing. So why are they automatically right about the subject of religion?