What is the sin of the good people at the great white throne?

Their sin is unbelief: they will not believe what God said concerning the work of the cross. Pardon has been accomplished through the death and resurrection of the Creator God, but they refuse to appropriate it by faith. It is not other wickedness, but failure to take God at His word.

Les explains that millions will come before the great white throne as good people, yet their sin is unbelief—the same controversy God had with Israel at Kadesh Barnea. Although He forgave their golden-calf immorality, He judged their refusal to take the land because they could not take Him at His word. These likewise cannot believe what God said concerning the work of the cross. Les acknowledges it is hard humanly to comprehend that the Creator God took on flesh, was crucified, and was raised, so God can pass salvation to the whole human race. The pardon is already accomplished; the only reason they do not receive it is that they will not appropriate it by faith.

Why will good people be condemned at the great white throne?

Good people are condemned at the great white throne because their sin is unbelief. Although the work of the cross has already accomplished pardon for every human being, they will not appropriate it by faith. They cannot believe what God has said concerning the cross, and that unbelief is their condemnation.