Certainly cowardice plays a large role here; in many cases a person's self-identity is also wrapped up on a person's religion.I think it is a form of cowardice. They find many of the Bibilical laws to be repugnant but they are not willing to renounce the buybull because they do not want to do anything that challenges what they are used to doing or believing in. I know that I went through that phase before converting and I believe you have as well, Both me and my twin started thinking and doubting our belief in a God during our teenage years after reading books on the buybull, doing soul searching, and reading about evolution. He came out as an atheist before I did. Whenever he would tell me that he did not believe in a god, I would call him a blasphemer, even though I doubted my own belief. I realize now that I was being a coward at that time. <quoted text>
And giving up the religion is akin to giving up one's identity.
But as Neil DeGrasse Tyson said?
He tries to live each day, learning something new.
If you are always learning something new? That will change a person's identity as sure as the sun sets in the west.
It may not be immediate, but learning new things will change a person for the rest of their life-- tiny incremental changes lead up to large, significant changes, given enough of them.