While suicide isn’t explicitly condemned in the Bible, it would be wickedly disingenuous to consider that God’s tacit approval of the act.  Pedophilia, same-sex marriage, abortion and other sins also aren’t explicitly named as sin, yet an honest reading of what God says on a host of other matters reveal his heart on these topics. First, there’s the fact that murder is an explicitly named sin (Exodus 20:13), and suicide is but self-murder. Second, it’s helpful to note that all instances of suicide in the Bible were carried out by those who were enemies of God, or those or who had turned away from Him. 

While it’s a popular in the world and among some Christians to absolve one of the sin of suicide if they suffered mental illness, there is no Biblical case for it. First, let’s highlight how there isn’t a single sin the Lord excuses because of one’s mental health. There is no such thing as “Go and sin no more, unless you’re mentally ill.” And we need to be honest -  what we count as “mental illness” is what the Scriptures count as spiritual oppression or double-mindedness (Judges 9:23; 1 Samuel 16:14-23; 1 Kings 18:21; Matthew 4:24, 5:15, 9:23; Mark 5 and elsewhere). Scripture says “a double-minded man is unstable in all his ways” (James 1:8). But there is hope, as the double-minded can be cleansed if they draw near to God (James 4:8).