My friend took her own life six years ago when we were both 17. She left me a note that said, "I have so many things I want to tell you, but I don't know how to say. If we can meet each other in this world again, I think at that time, we can talk whatever we want." Apparently she was tired of this world and wanted to go. Actually, I slit my wrist once when I was 14. I want to know, if a person doesn't want to live any more and if suicide is the only way out, why don't we let her go? Why are Christians so harsh on the one comitting sucide? I just don't understand most people who curl up in a hospital and wait their death. A person committing suicide faces death actively. Why do some people think it's unforgivable? Is it wrong to cross the street when the traffic light turns red?
Allow me to place your questions in another situation. Suppose a person is tired of being bothered by another person, so he kills that person. Could the murderer claim that it is my life, and I can do with it as I please? Since the other person was interfering with the murderer's life, does that give the murderer the right to end another person's life?
I hope you are answering "No!" In fact, you are probably saying, "That is not the same situation! One person doesn't have the right to decide when another person's life should end." True! And that is the crux of the problem. Your questions make two assumptions: First, you assume that a person has the right to end their own life if they so chose. Second, you assume that suicide, at least in some cases, "is the only way out."
Christians understand that we are not here by our own will. We are placed in this world for a purpose. "Let us hear the conclusion of the whole matter: fear God and keep His commandments, for this is man's all. For God will bring every work into judgment, including every secret thing, whether good or evil" (Ecclesiastes 12:13-14). Christians understand that our lives are not our own to misuse as we please. "Or do you not know that your body is the temple of the Holy Spirit who is in you, whom you have from God, and you are not your own? For you were bought at a price; therefore glorify God in your body and in your spirit, which are God's" (I Corinthians 6:19-20). Thus a person committing suicide is no different from a person killing another person, both have no right to ending a person's life.
The second mistake is that suicide is the only way out. Since when? Suicide is an attempt to escape perceived problems, but it never solves a problem. It is only a cowardly way to avoid facing a problem. Why should anyone praise another for being a coward? "But the cowardly, unbelieving, abominable, murderers, sexually immoral, sorcerers, idolaters, and all liars shall have their part in the lake which burns with fire and brimstone, which is the second death" (Revelation 20:8).
As with all of life's problems, there are always alternatives. Not all alternatives will necessarily be pleasant, but there is always a choice. The one contemplating suicide has the choice to face his problems and work to solve them. "No temptation has overtaken you except such as is common to man; but God is faithful, who will not allow you to be tempted beyond what you are able, but with the temptation will also make the way of escape, that you may be able to bear it" (I Corinthians 10:13). If you understand, as I do, that suicide is a sin, then you understand that those tempted to commit suicide were offered a way to face their problem with ending their life. There was a way that the problem could have been borne.
The reason it is considered unforgivable for the one that successfully commits suicide is that there is no opportunity to ask God for forgiveness. It is impossible to repent of a sin when you are already dead.