Hell itself is nothing but truth known too late.

Our Lord tells us that in the day of His second coming, ''Many will seek to enter in at the strait gate, and shall not be able." [Luke 13:24] They will "knock at the door, saying, Lord, Lord, open to us," [v. 25] but will find no admission. They will even plead earnestly, that "they have eaten and drunk in Christ's presence, and that he has taught in their streets." [v. 26] But their plea will be unavailing. They will receive the solemn answer, "I don't know you. Go away, all you who do evil." [v. 27] Religious profession, and formal knowledge of Christ will save none who have served sin and the world.

There is something peculiarly striking in our Lord's language in this prophecy. It reveals to us the dreadful fact, that men may see what is right when it is too late for them to be saved. There is a time coming when many will repent too late, and believe too late—sorrow for sin too late, and begin to pray too late—be anxious about salvation too late, and long for heaven too late. Myriads shall wake up in another world, and be convinced of truths which on earth they refused to believe. Earth is the only place in God's creation where there is any infidelity. Hell itself is nothing but truth known too late.

—J.C. Ryle, 'Expository Thoughts on Luke’