Very early on in the ministry of teaching the Scriptures as a pastor, I had to have an answer to the suicide of a Christian. In my search for God's answer, I found 1 Corinthians 3:13-17.
1Co 3:13 each one's work will become manifest, for the Day will disclose it, because it will be revealed by fire, and the fire will test what sort of work each one has done.
1Co 3:14 If the work that anyone has built on the foundation survives, he will receive a reward.
1Co 3:15 If anyone's work is burned up, he will suffer loss, though he himself will be saved, but only as through fire.
1Co 3:16 Do you not know that you are God's temple and that God's Spirit dwells in you?
1Co 3:17 If anyone destroys God's temple, God will destroy him. For God's temple is holy, and you are that temple.(ESV)
I have found that so many of our modern theologians stick mostly in the New Testament for their theology. They rely on the tender mercies and grace of our Lord in giving answers to these hard questions. It is, IMO, hard to find a theology that has a balance of O.T. & N.T. doctrine.
For me? It is critical that I have BALANCE! There must be a proper fear of the Lord! He is the One Who calls the shots, not us.
Mat 10:28 And do not fear those who kill the body but cannot kill the soul. Rather fear him who can destroy both soul and body in hell.
Those of us who have been studying the O.T. have discovered a side of God that is not expressed in the N.T. as it is in the O.T. Therefore we get a one sided opinion of the nature of the Almighty God we serve. We are to serve Him the way He instructs. If we decide to go to the left or right of His narrow road, we do so at our peril. If we stay on the path that He demands, we will make it to our Promised Land. Heaven will be occupied with those who Love God with all their heart, mind, body, strength, and will. That means with all that we are, we belong to Him and do what He wants, not what the flesh wills.
I have said all this to say, I do not believe that a person who commits suicide will inherit eternal life! The Scripture is clear to me. The context of 1 Corinthians 3:13-17 is clear. We are looking at heavenly occupation and reward. The reward for destroying the residing place of the Holy Spirit, where He carries out the ministry of Jesus the Christ is a great sin against God. It classifies as the unforgivable sin because it attacks the Holy Spirit of God. Any speech or act against the Holy Spirit will bring the wrath of Almighty God, we Christians must not gloss over that in being a respecter of people or theology.
I personally believe, as I have stated before, it is possible for a person who claims to be saved, to loose that position by rejecting Jesus Christ and His Counselor, the Holy Spirit. They are God, they are one, they must be respected and feared. We show our respect by worshiping Jesus in the power of the Holy Spirit. We demonstrate our fear the Lord, by not wanting to sin against Gods Commands, statues, and rules. We fear the results of Gods displeasure.