There’s not a great deal in scripture about it but the Catechism references the following verses from 1 John 5:
**16 If you see any brother or sister commit a sin that does not lead to death, you should pray and God will give them life. I refer to those whose sin does not lead to death. There is a sin that leads to death. I am not saying that you should pray about that. 17 All wrongdoing is sin, and there is sin that does not lead to death. **
Thank you very much. I think this is the answer my friend is looking for. God bless you!