Question: There are many who advocate that a born-again believer in Christ can commit suicide and still be saved. They stress the fact that there is only one sin that God will not forgive: blaspheming the Holy Spirit. They use King Saul, Samson, and Judas Iscariot. My thought on this is that no saint can/could ever give up on life, self, or God because His Spirit is in them and is the Life of the believer. The works of the flesh are described in Galatians:5:19-21a. Could you explain the differences between these three men (Samson, Judas, and King Saul) as to what their deaths proved? Is it possible for a saint to commit suicide?
Response: The answer to your question has little to do with King Saul, Samson, nor especially Judas. The answer is predicated upon this biblical absolute: Everyone who is truly born again, who has by grace alone through faith alone believed that Jesus paid the full penalty for one's sins (which He did—past, present, and future!) has therefore received the gift of eternal life.
One might as well ask if a saint of God could commit adultery, steal, or even murder. Tragically, it has proved to be possible for Christians to commit all manner of wickedness. Such is the nature of mankind, whose heart is "deceitful above all things, and desperately wicked" (Jeremiah:17:9). As such a person goes through life and, for whatever reasons, is overtaken by the world, the flesh, or the devil—even to the point of suicide—his fruitfulness in life and his eternal rewards will be affected, but it cannot affect his gift of eternal life, which he neither earned nor could pay for.
A believer who is truly saved and maturing in Christ should not desire to commit any sin. The Word of God abounds in exhortations directed at believers to live their temporal life for Christ, to fight the good fight of faith, to beware of the wiles of the devil, who goes about seeking whom he may devour, etc. There would be no such admonitions directed at believers if they were immune to those things that would shipwreck their faith. But as God's Word repeatedly affirms, we are assured that His gift of eternal life extends even to those saints who fail.