Is it counted a sin if you kill yourself to make universal peace?

Answer 1

If you have unforgiven sins when you die, you go to hell, so by killing yourself, you are committing a sin. You can not have that sin, obviously, because you are dead. Whether you are wondering out of curiousity, or because you are having thoughts of suicide, please do not kill yourself. People do not think they do, but everyone has someone that loves them.

Answer 2

The Ten Commandments injunction, "Thou shalt not kill" applies just as much to killing yourself as to killing others. If you believe in eternal life, the answer is, there is never a reason that God will accept for killing yourself. And certainly, killing yourself will not result in eternal peace.
If you are depressed about anything, I strongly urge you to talk to a trusted counsellor or friend. Depression is an acknowledged medical condition and not something to be ashamed of. Some people suffer from ongoing bouts of depression, others have mood swings, between elation and the severest depression. It is important not to diagnose yourself, perhaps rationalising that this description is not you. Seek medical help. Once depression is managed, I'm sure you will be amazed at the change in your world view.