William Burkitt on Jude 1:12

Our apostle having set forth these seducers in the foregoing verses by sundry examples, he now comes to set them forth by several similitudes and resemblances.

1. He calls them spots in their love-feasts, (the infamy of their lives being a blemish and scandal to their Christian assemblies,) feeding without fear either of offending God or man.

2. He calls them clouds without water, promising rain, but yielding none; making a show of knowledge, but indeed having none; and they are driven (as clouds by the wind) from one vanity to another.

3. Trees they are, but like them in autumn which have neither leaves nor fruit: nay, trees twice dead, in sin before conversion, and in respect of their apostasy after their conversion, and so shall be plucked up by the roots.

4. They are like raging waves of the sea, turbulent and tumultuous, foaming out at their mouths the filthiness and impurity that boileth in their hearts.

5. Wandering stars, or teachers unstable, departing from the true faith once delivered to them; but for these illuminated and knowing teachers is reserved the blackness of darkness for ever.