In verse 12 they are called natural brute beasts. This would mean there is no spiritual nature energized by the Holy Spirit of God. You will notice they speak evil of things they do not understand and how could they because they are spiritually discerned. Without the new nature and God's Spirit how can we understand anything.
Next we have their characteristics. Eyes full of adultery. Adultery here not the max woman type, but away from God the true husband of the Church. They beguile unstable souls maybe saved maybe not saved. They have a heart trained in evil practices and are accursed meaning no salvation.
Now the comparison is Balaam, a so called prophet of his own making not energized by God, paid to curse the people of God. If he was real he couldn't have conscientiously have done what he did. Peter calls it madness. Even being warned by a dead animal.