Answering the question of why correct belief is the criteria for being judged for eternity requires laying a foundation so that the answer makes sense within a Christian perspective. In Christian theology, God is holy and righteous. His Holiness means he cannot sin and his righteousness means that he must do what is right. When we sin we break the Law of God, and we are in effect challenging the holiness of God. Therefore, because he is righteous, he must punish the sinner. If he did not, then he would not be righteous because he would be allowing sin to flourish without being dealt with.
Therefore, we must find a way to escape the righteous judgment of God. Biblically, there are two ways to do this: faith and works. Let’s take a look at works first.
If we are to seek to escape the righteous judgment of God, then our works must be perfect. We must never sin. We must never break God’s Law (such as the Ten Commandments). As soon as we break one of his laws, there is a required judgment. After all, laws have punishments. If there is no punishment for lying when the Bible says “You shall not lie,” then all we have is a recommendation and not a law.
Since we have sinned against God who is infinite, then the consequence of our sin against him is also infinite. Let me explain. If I were to slap you in the face, you might get upset with me or slap me back. If I were to slap the president of the United States in the face, it would be a felony, and I would go to prison. Why does the exact same action get such different results? It is because of who the offense is against. The higher up the chain of authority, the more severe the consequence. Likewise, when we move up the chain of authority to the infinitely holy God, the offense (i.e., lying, stealing, cheating, etc.) results in an infinite consequence. That consequence is eternal damnation. In order to escape this judgment, we must never break any of God’s laws. We must work perfectly. Unfortunately, none of us does that, which means we all deserve the eternal judgment of God.
The solution to our problem is found not in our keeping of God’s Law, but in trusting what Jesus did for us–where he kept the Law. Jesus is God in flesh (John 1:1, 14; Colossians 2:9). He is the one who fulfilled the Law of God perfectly. He never sinned, but he did bear our sins in his body on the cross (1 Peter 2:24) where he died, and then rose from the dead (1 Corinthians 15:1-4). Since Jesus is the one who did everything that was necessary in keeping the Law that we can’t, then we must have faith and trust in what Jesus did on the cross on our behalf.
Therefore, our faith becomes the only means by which we can appropriate the saving work of God – by trusting in what Christ did, not what we can’t do. Faith becomes critical, and whom our faith is in is equally critical. Belief and trust in something or someone false is useless. For example, if I have all the faith in the world that a particular chair will support me when I sit in it, but the chair is incapable of doing so because it is faulty, then when I sit in it I will fall. So, faith is only as good is who (or what) you put it in. Likewise, faith in the true and living God is necessary, and not faith in a false god.
Correct faith is faith in the true God, not a false god. There are many false gods in the world, such as the God of Mormonism who is an exalted man from another planet; or the God of Jehovah’s Witnesses, and the Muslims who deny that Jesus is divine and also deny that God is a Trinity.
Finally, Jesus said, “Unless you believe that I am, you will die in your sins,” (John 8:24). Later in that same chapter in John 8:58, Jesus said: “before Abraham was, I am.” This is particularly important when we understand that immediately after Jesus said this the Jews wanted to kill him. But Jesus escaped. What was Jesus saying that was so incendiary? When we realize that when Moses was at the Burning Bush, and he asked God what his name was, God said “I am that I am. Thus you shall say to the sons of Israel, I am has sent me to you,” (Exodus 3:14). Jesus was claiming to be the great “I am.”
So, Jesus Himself is stating that we must have proper faith in who He is, namely, that He is God in flesh. True faith in the true God necessitates that we affirm Jesus Christ as God in flesh. If we don’t, according to Jesus’ own words, we will die in our sins.
