If you are part of a religion that very strongly insists that you believe then to decide not to do that is quite a big hurdle to jump over. You never forget the thought process you went through. It becomes part of your whole intellectual picture. ↗
In other words, a person who is fanatic in matters of religion, and clings to certain ideas about the nature of God and the universe, becomes a person who has no faith at all. ↗
And learn that when you do make a mistake, you'll surface that mistake so you can get it corrected, rather than trying to hide it and bury it, and it becomes a much bigger mistake, and maybe a fatal mistake. ↗