“But these speak evil of whatever they do not know; and whatever they know naturally, like brute beasts, in these things they corrupt themselves.”  

But these speak evil of whatever they do not know;

We come to the fifth earmark of apostates–they criticize what they do not know.

Michael, the archangel, did not dare challenge the devil, but apostates dare to blaspheme (Greek) what they do not know. This word “know” is mental comprehension. What “they do not know” is the Word of God. The pride in Gnosticism lies in their so-called special knowledge, but Jude challenges this specious knowledge.

and whatever they know naturally,

Apostate knowledge is only natural. This second word for “know” means to understand. This knowing is more skill and refers to palpable things, objects of sense. All these apostates know is what they can see.

like brute beasts,

Their knowledge operates more like animal instinct than rational knowledge. “Brute” is literally without thought. They operate without rational thought.

in these things they corrupt themselves.

Apostate knowledge corrodes from within. “Corrupt” means destroy. They destroy themselves from within by their peculiar system of knowledge.

PRINCIPLE:

People often criticize things they know nothing about.

APPLICATION:

Apostates often operate mindlessly like unreasonable animals. Their problem is that they do not have a divine capacity to understand the things of God. They are pure “natural man” without a spiritual capacity (new nature) to understand divine truth.

But the natural man does not receive the things of the Spirit of God, for they are foolishness to him; nor can he know them, because they are spiritually discerned. 1 Co 2:14