What does the Bible say about worrying about eternity?

The Bible acknowledges the reality of worry regarding eternity, especially concerning our mortal nature and ultimate judgment before God. In Hebrews 9:27, it is appointed for man to die once, and after that comes judgment. Healthy concern for our eternal state leads us to seek reconciliation with God, which is paramount, given His holiness and justice. Jesus warns in Matthew 7:21-23 about those who, despite performing religious activities, will be cast away if they have not obeyed the gospel of grace. Therefore, being concerned about one's eternal soul is not only appropriate but essential for salvation.