I've heard a really good analogy for this that made me understand it better, myself. Perhaps it will help you understand. (And just to be clear, I'm not trying to push you to agree or believe or whatever. But it's good to understand something fully before you reject it.) I've heard it described this way (very simplistic, so please, theologians, don't get your panties in a bunch over the lack of details). Basically, God has a law, or a code, or whatever you want to call it. If we look at the 10 Commandments alone, EVERY single person on the planet has broken at least one of them, without a doubt. Nobody is perfect. So, given that we have all broken the law, we are all destined for prison. That's justice. God would not be a just being if He didn't sentence us to pay for breaking the law. The reason Jesus fixes the "problem" is because he takes on all of our punishment for us -- for all of humanity, past, present, and future. He did the time for us. He posted our bail, if you will, and now we are able to have freedom and spend eternity in Heaven, rather than the prison. All we have to do is accept his offer, like accepting a plea deal in a court case. This is because of the Grace of God that we have this option. Some people say that God is cruel for sentencing us all to hell, but first of all, paying for our crime in breaking his law is just, and secondly, he gives us a completely free, easy (for us... it certainly wasn't easy for him or for his Son) gift that washes our slates completely clean. If God was not loving, we wouldn't have that option. There would be no opportunity for sinners like all of us to be in His presence and have a relationship with Him. We all broke the law, we would all go to prison. Simple as that. But because He is loving, He made a tremendous sacrifice in order for us to have freedom, simply by accepting His offer. I love law stuff, so that analogy has always stuck with me. Hopefully it gives you some more understanding of how and why that works the way it does.