Jude 23

In the Epistle of Jude, Jude is writing against different types of false brethren within the church, and exhorting the church to be faithful. Verses 22 and 23 contain Jude's instructions on how the church should respond to the false brethren and/or to those within the church who have been influenced by their teachings ("those who are doubting"). It does appear that there is some progression in the three types of these doubters. Some are to be shown mercy, presumably so that they may stop doubting. Others are to be snatched from the fire and saved, probably indicating that their doubt is so great that they are in danger of perishing for want of belief. Others are to be shown mercy with fear, but the exact reason for this fear is not explicit. Probably, they are the worst of the lot, and have carried their doubt to the point of rejecting righteous living, casting themselves into sin (e.g. vv. 4,7-8,15-16). It would seem reasonable to exhibit proper "fear" in dealing with these people so as not to fall into the same sins (cf. Gal. 6:1).

It does not seem likely that any of these are committing the sin unto death, because those who commit that sin are beyond hope (1 John 5:16). Jude's warnings and instructions seem designed to inspire change, which implies hope of a better state.