Why did God judge the Israelites at the golden calf?

Les teaches that not only did the Israelites make the golden calf, but their behavior around it was abject immorality, which was always part and parcel of idolatry. They were in stark nakedness, and God judged them for it, so a few thousand died because of it. However, Les contrasts this with what happened later at Kadesh Barnea: it was not the unbelief practiced around the golden calf that brought in the wrath of God, for that was easy for Him to forgive. Instead, God's controversy was their unbelief that they could not take the land He said they could. It was that they could not take Him at His word. Les says it will be the same with millions before the great white throne—good people whose sin is unbelief, not believing what God said concerning the work of the cross. Their pardon is accomplished, but they will not appropriate it by faith.