2 Peter 2:20-22

Now, if, having fled away from the pollutions of the world, through the knowledge of the Lord and Saviour Jesus Christ, and being again entangled, they are overcome by them; their last condition is worse than the first.

1 John 2:19

They went away from us, but they were not of us. For, if they had been of us, they would have abode with us; but they went away, that they might be made manifest that they were not of us.

Treasury of Scripture Knowledge

Summary

When I shall say to the righteous, that he shall surely live; if he trust to his own righteousness, and commit iniquity, all his righteousnesses shall not be remembered; but for his iniquity that he hath committed, he shall die for it.

Bible References

If he

2 Peter 2:20
Now, if, having fled away from the pollutions of the world, through the knowledge of the Lord and Saviour Jesus Christ, and being again entangled, they are overcome by them; their last condition is worse than the first.
1 John 2:19
They went away from us, but they were not of us. For, if they had been of us, they would have abode with us; but they went away, that they might be made manifest that they were not of us.