In John 8:24 Jesus says, “Therefore, I said to you that you will die in your sins; for unless you believe that I am He, you will die in your sins.” So [another] way to guarantee you will die in your sins is to be unbelieving of the gospel. You don’t have to go out and kill someone and be bad to go to hell, because hell is not just for criminals, it is for everyone and anyone who refuses Christ. If you refuse Christ in this life, God isn’t going to force you to dwell with Him forever in eternity.

You say, “What am I supposed to believe?” I remember a song that used to be popular, called “I Believe,” which kept on repeating the words “I believe.” I believe what? Another song is “I Believe in Music.” If that is all you believe in, you’re in trouble. You find the same kind of vague or misdirected faith when you ask people, “Do you believe in Christ?” “Yeah, I believe in Christ, He lived and so forth.” But Jesus had something more definite in mind. Notice what He says, “Unless you believe that I am He.”

It isn’t enough to believe that Jesus is the One that you think He is; you must believe that He is the One He claimed to be. He claimed to be God by such phrases as, “I am the bread of life” (John. 6:35), “he who believes in Me will never thirst” (6:35), “I am the Light of the world” (8:12), “I am the good shepherd” (10:11), “I am the door” (10:9), “I am the resurrection, and the life” (11:25), “I am the way, the truth, and the life” (14:6).

Because Jesus was identifying Himself with God, saving faith not only becomes a question of turning from sin, but trusting the Son as well. It’s a question of believing Jesus is who He claimed to be. You ask, “Am I going to die in my sin unless I believe that He is all that He claimed to be?” That’s right. You ought to find out who He claimed to be, for Romans 10:17 says faith comes by hearing a message about Christ. You can never have true faith unless you hear the truth about Christ.

True faith is the result of hearing and believing with your heart that Jesus is who He claimed to be, and that God verified that claim by raising Him from the dead (Rom. 10:9). Jesus promises His opponents that they will die with their sin unforgiven if they do not believe that He is who He claims to be– God in human flesh. Not to believe and turn away shatters hope and leaves only hell’s gloomy foreboding. (John MacArthur, Truth Endures, 98, 99; excerpted from The Reality of Sin: The Simple Gospel)