Before you justify certain acts such as excessive drinking, suicide or polygamy based on the fact that they were done in the Old Testament, you need to take time to understand things. It is important to understand from the two perspectives: Old Covenant and the New Covenant. Now, let me state clearly that judgement ultimately lies with the LORD, but the Christian is called to be wise too.
Secondly, Judas Iscariot, Sampson, Saul, etc. who all committed suicides in the past did so under the Old Covenant (i.e. The Old Testament). Abraham, David, Solomon, etc. who all married many wives did so under the Old Covenant. The New Covenant (aka The New Testament) started with the death and resurrection of Jesus Christ.
“And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance. For where a testament is, there must also of necessity be the death of the testator”, (Hebrews 9:15-16). There you have it. The New Covenant started with the death of Jesus Christ.
Thirdly, prior to the New Testament, God overlooked certain things due to ignorance. We are therefore told that those who did these things ignorantly were overlooked by God. “And the times of this ignorance God winked at; but now commandeth all men every where to repent“, (Acts 17:30).
Since God is a God of mercy, justice and fairness, He gave even those who died under the Old Testament a chance for repentance. When Jesus died, He went and preached to them all. “After being made alive, he went and made proclamation to the imprisoned spirits“, (1 Peter 3:19)
So, those who did these things under the Old Testament did it ignorantly. But we have no excuse, and God will no longer wink at it, (Acts 17:30-31). Because, there is no more repentance in the grave. Above all, you now know the truth and cannot feign ignorance. This warning is to us all: “For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins“, (Hebrews 10:26).
May the Spirit of God continue to water His word in your heart that you may abound bountifully.