"Unto Him, who is able to keep us"
The Spirit of God in this epistle [Jude] does not bring forward the efficacy of this redemption. He is occupied with the crafty devices of the enemy, with his efforts to connect the actings of the human will with the profession of the grace of God, and thus to bring about the corruption of the assembly, and the downfall of Christians, by putting them on the road to apostasy and judgment. Confidence is in God; to Him the sacred writer addresses himself in closing his epistle, as he thinks of the faithful to whom he was writing. Unto Him, he says, who is able to keep us from falling, and to present us unspotted before the presence of His glory with exceeding joy.
From: Synopsis of the Books of the Bible, Jude's Epistle, by J N Darby