"Keep yourselves in the love of God, waiting for the mercy of our Lord Jesus Christ that leads to eternal life. And have mercy on those who doubt; save others by snatching them out of the fire; to others show mercy with fear, hating even the garment stained by the flesh."
It can be difficult in our minds, hearts, and attitudes to distinguish between the sin and the sinner. While hating "even the garment stained by the flesh," we are to show mercy to doubters. This isn't easy. There is a lot to consider and pray about in these verses, and I do not pretend to understand it completely, but it does remind me to love others while hating the sin. We are to do what we can to snatch "them out of the fire," but whatever course they decide, we must be merciful and remember that we are not the Judge.
One Thing: Show mercy and love toward doubters -- but with fearful understanding of the spiritual danger they are in.