Multiple reasons why actually. I'll name a few.
1. I'm gæ (gay)
2.If god was so good then why would he make so many of his children suffer. Then send them to hell when they couldnt take it
3. If god is in control, why are there so many bad things happening 24/7
4. I know I'm going to hell and there is not hope for me so, what's the point?
5. Cant find any evidence
6. Bad/Greedy priests. Once at a funeral someone asked the priest to send a prayer to the lost family member to help them get to heaven , the priest asked for money on the spot.
7.Getting married is a promise to god, so a married Christian couple have to stay together so they dont rot in hell, even if they are married to a really bad person.
8. When I was younger, my grandparents would constantly tell me I'm going to hell for the smallest things, like playing with a magic eight ball.
9.Guess who never had my back/ never answered my prayers? God!
10. Tried on and off to read the bible, god always sounded selfish to me.
11. The most innocent people who have done nothing wrong will be sent to hell for having a different religion.