We All Have Sinned
Romans 3:23 tells us "For all have sinned, and come short of the glory of God." Each of us have broken God's law. No one is perfect.
We Must Pay For Our Sin
The Bible says in Romans 6:23a "The wages of sin is death." Because we are not perfect, we are bound for hell. The 'payment' of our sin is death in hell. But God doesn't want that for us.
God Took Our Punishment
The Bible says in Romans 5:8 "But God commendeth His love toward us, in that, while we were yet sinners, Christ died for us." Because God loved us, He sent His son to die on the Cross for us, to pay for our Sin.