Basically not 100% certain because if God (or any divine being) is capable of creating the universe then why would it not be possible for them to create a 'history' that preceeds the actual age of the world. I don't believe this, but don't see any reason why it couldn't happen if God is all powerful etc.
Yes this is called faith.
There is absolutely nothing to suggest such an event, except that it was once told as a story and written in a book eventually after many generations of word of mouth learning. Then two major offshoot breakaway sects modified that text for their own faith.
There is no evidence at all for this, except their faith.
Some of the offshoots don't even believe it directly as verbatim word, more treat it as a story to explain how God would create the universe, the Catholic Church being in this latter group. Believing in the scientific basis of the universe around us.
In some churchs it is down to individual ministers to decide if the creationism story is the stalwart of faith, or a story.
Faith.
It removes any need to think about anything, or worry about anything, just have faith and something something.
People may have faith, fine , if that is how they wish to perceive their existance.
It shouldn't be a bloody government policy.
Not anywhere, not due to any religion.