You cannot walk in the light accidentally. To continue in the light, you must deliberately avoid darkness. God's promise to forgive is conditioned upon confession. You cannot confess a sin of which you are ignorant. Our criminal code is based on the principle that men should be punished in a manner commensurate with their guilt.
Guilt is determined by the responsibility of the person accused.
Notice that no guilty person was excused. All received punishment portioned to their powers, opportunities, and knowledge. Each passing day erodes any legitimate appeal to ignorance. There are different levels of knowledge, degrees of preparation, and varying amounts of service rendered among Christians. These differences will be factored into the administration of rewards and punishments.