Is the sin debt paid in full?
Yes, the debt is paid in full through the atoning blood, but God cannot activate that payment until a person believes the Gospel. For those who believe, they are totally forgiven; their sins are taken care of, forgiven, and canceled.
Les explains that people who go into a lost eternity do so not because their sins weren't taken care of or because the atoning blood wasn't for them, but because they rejected it in unbelief. He emphasizes that the sin debt is paid in full, yet God cannot activate that payment until a person believes the Gospel. Belief must come before appropriating forgiveness. For those who believe, they are totally forgiven. Les also points to Colossians 3:13, where believers are to forgive one another as Christ forgave them, and notes that at the bema seat, believers will not have to face their sin because it is taken care of, forgiven, and canceled.