Jude 1:1 - Coke's Commentary on the Holy Bible

And brother of James,— He might also have called himself the brother of our Lord, for he was nearly related to the Lord Jesus Christ, according to the flesh; but though the evangelists have given them that title, yet neither Jude, nor his brother James, have ever taken it to themselves: perhaps they avoided it out of their great humility, or to intimate that, though they had known Christ after the flesh, or valued themselves for being related to him, yet now henceforth they knew him so no more, nor valued themselves so much upon that account, as in their being his faithful servants. Preserved in Jesus Christ, means, "preserved in that hour of temptation, when so many false teachers had corrupted the gospel, and such numbers of Christians had fallen from the purity of it." As they retained their integrity, they would be preserved from the judgments which were coming upon those who had fallen away; and they might depend upon it, that, if faithful unto death, they should in due time receive their reward.