Jude 1:5

Now I desire to put you in remembrance, though ye know all things once for all, that the Lord, having saved a people out of the land of Egypt, afterward destroyed them that believed not.

Though ye know all things once for all ... Here again is (Greek: [@hapax]), indicating that the Christian knows the whole message once and for all, finally, before he is even converted. In the sense of its basics, the Christian faith is not an exploration, but an acceptance, but not so much after that acceptance a learning, as it is a doing. Barnett defended the RSV as superior in their rendition of this as, "Learn one lesson, and you know all."[21] This applies to the "common salvation" and the "faith once for all delivered" rather than to the Old Testament examples Jude was about to cite.

Saved a people out of... Egypt ... By bringing up the example of the Israel of the Exodus, Jude taught that, "The goodness of God will not hinder him from punishing the wicked under the new dispensation, any more than it hindered him from punishing them under the old."[22]

The information which Jude states in this verse as being known "once for all," according to Wheaton, is "catechetical instruction given prior to baptism,"[23] which corresponds with the meaning suggested in discussion of it above.

Afterward destroyed them that believed not ... Here the New Testament habit of using "belief" to cover a whole family of related things is clear enough. The Israelites were destroyed for idolatry in worshipping the golden calf, their fornication with the Midianites, their murmuring and complaining, etc.; but all of this is summed up as "they believed not."

[21] Albert E. Barnett, The Interpreter's Bible, Vol. XII (New York and Nashville: Abingdon Press, 1956), p. 326.

[22] James MacKnight, op. cit., p. 194.

[23] David H. Wheaton, op. cit., p. 1275.