Albert Barnes Commentary Jude 1:22

"And on some have mercy, who are in doubt;" — Jude 1:22 (ASV)

And of some have compassion. This cannot be intended to teach that they were not to have compassion for all people, or to regard the salvation of all with concern, but that they were to have special and particular compassion for a certain class of persons, or were to approach them with feelings appropriate to their condition.

The idea is that the specific feeling to be shown toward a certain class of persons in seeking their salvation was tender affection and kindness. They were to approach them in the gentlest manner, appealing to them with such words as love would prompt. In contrast, others were to be approached in a different manner, indicated by the phrase save with fear. The class referred to here, to whom pity (Greek: eleeite) was to be shown, and in whose conversion and salvation tender compassion was to be employed, appears to have been: the timid, the gentle, and the unwary; those who had not yet fallen into dangerous errors but who might be exposed to them; and those (for such people exist) who would be more likely to be influenced by kind words and a gentle manner than by denunciation.

The direction, then, amounts to this: while we are to seek to save all, we are to adapt ourselves wisely to the character and circumstances of those whom we seek to save (See Barnes, 1 Corinthians 9:19 and following).

Making a difference. This means making a distinction between them, not in regard to your desires for their salvation or your efforts to save them, but in regard to the manner in which it is done. To be able to do this is one of the highest qualifications to be sought by one who endeavors to save souls and is indispensable for a good minister of the gospel. The young, the tender, the delicate, the refined, need a different kind of treatment from the rough, the uncultivated, the hardened. This wisdom was shown by the Savior in all his preaching; it was eminent in the preaching of Paul.