There are those who fall to temptation and get up (repent) and there are those for whom cherished sin is a way of llife. They love to wallow in the mire but think that their good works balance out their bad works and so they think they are ok.
Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
Matthew 7:22
The thing that amazes me about this is that it implies that they actually did wonderful miracles, that they were spokesmen or prophets for God and did cast out devils and that they worked hard for God. It implies that their work was good work. But this didn't earn them salvation because God says He never knew them. Wrong motives for their work? Clinging to sin? Not loving others as themselves? Not loving the Lord with all their heart and soul? Pride?