"For the time has come for judgment to begin at the house of God; and if it begins with us first, what will be the end of those who do not obey the gospel of God? Now 'If the righteous one is scarcely saved, where will the ungodly and the sinner appear?'" (1 Pet. 4:17-18)

Apart from obedience to the gospel, there is no promise of forgiveness. In effect, the sinner of the world who hasn't obeyed the Lord is depending on his own moral goodness to save himself. However, no one can be saved by his own moral goodness. Let's suppose that someone has a sour lemon tree in his back yard, but he doesn't want a sour lemon tree; he wants a sweet orange tree. Thus, he pulls off all the sour lemons and ties oranges in their place. Does he now have a sweet orange tree? No; in reality, all he has is a sour lemon tree with oranges tied on it. So it is when one is depending on his own moral goodness without changing his state before God.