Jude calls the false teachers "brute beasts," just as Paul called them "savage wolves" (Acts 20:29) and Jesus called them "ravenous wolves" "in sheep's clothing" (Matthew 7:15). They have sunk down to the level of animals in that their only desire is to satiate their lusts, the drives that we share with animal kind: food, security, sex, power, authority, prestige. They really cannot comprehend the higher values because they only think in terms of gratifying themselves. If one attempts to convince them of their error from the Scripture, they will never get it because they simply do not care. All they want is what they think is theirs—their position, their food, their sexual gratifcation, their prestige. The object of their desire makes no difference. If they want it, if they feel they need it, no one can convince them from pursuing it in most cases because they are on an entirely different—lower—level. They are being driven purely by their physical desires.
Paul ran into this problem in Corinth. Notice I Corinthians 15:32—34:
If in the manner of men I have fought with beasts at Ephesus, what advantage is it to me? If the dead do not rise, Let us eat and drink, for tomorrow we die. Do not be deceived: Evil company corrupts good habits. Awake to righteousness, and do not sin; for some do not have the knowledge of God. I speak this to your shame.
People in Corinth were already using such fallacious arguments as saying the resurrection was already past in order to do whatever they wanted to do sexually, or as Paul mentions in chapter 11, to gorge themselves at the feasts and drink until they could hardly stand. The idea here is they used illogic, as far as we are concerned, to justify doing whatever they pleased. It is almost impossible to talk such people out of what they are doing.
Richard T. Ritenbaugh