As Christians, we are our brother’s keeper.
16 If you see a fellow believer sinning in a way that does not lead to death, you should pray, and God will give that person life. But there is a sin that leads to death, and I am not saying you should pray for those who commit it. 17 All wicked actions are sin, but not every sin leads to death. (1 John 5: 16-17, NLT)
The passage above says “if you see”. This suggests that we might see our brothers and sisters in Christ displaying wicked actions, and if we do, we are not just to turn a blind eye (as is so often the custom in the church today).
There is only one (“a”) sin that leads to death, which suggests that the majority of sins do not end in death (eternal separation from God). That being said, all sin is sin and God does not want His children to live that way. As fellow believers, we can pray for each other if we see something out of turn in our brethren’s life and God will give that person the grace they need to come out of that lifestyle.