John Calvin Commentary Jude 1:13

"Wild waves of the sea, foaming out their own shame; wandering stars, for whom the blackness of darkness hath been reserved forever." — Jude 1:13 (ASV)

Raging waves of the sea. Why this was added, we may learn more fully from the words of Peter (2 Peter 2:17–18): it was to show that, inflated with pride, they breathed out, or rather cast out, the scum of their high-flown, grandiloquent language. At the same time, they produced nothing spiritual; on the contrary, their object was to make people as stupid as brute animals.

Such, as has been previously stated, are the fanatics of our day, who call themselves Libertines. You may justly say that they make only rumbling sounds; for, despising common language, they form for themselves an exotic idiom, of what kind I do not know. They seem at one time to carry their disciples above heaven, then they suddenly fall into beastly errors, for they imagine a state of innocence in which there is no difference between depravity and integrity; they imagine a spiritual life when fear is extinguished and when everyone heedlessly indulges himself; they imagine that we become gods because God absorbs the spirits when they leave their bodies.

Therefore, the simplicity of Scripture ought to be studied with greater care and reverence, lest by reasoning more subtly than is appropriate, we might not draw people to heaven but instead become entangled in complex labyrinths. He therefore calls them wandering stars, because they dazzled the eyes with a kind of fleeting light.