Jude 16 - 19

16 These are grumblers, complainers, walking according to their own lusts; and they mouth great swelling words, flattering people to gain advantage. 17 But you, beloved, remember the words which were spoken before by the apostles of our Lord Jesus Christ: 18 how they told you that there would be mockers in the last time who would walk according to their own ungodly lusts. 19 These are sensual persons, who cause divisions, not having the Spirit.

Jude is still writing about the deceptive false teachers who have snuck into the church. (verse 4) To satisfy their own desires they grumble and complain about the gospel and the church. They are great speakers and can deceive with the magnificence of their speaking abilities which they use to flatter the members of the church to deceive them into believing their false doctrines.

Jude says to remember the teaching of the apostles who warned about those who would try to change the teaching and practices of Christ and the apostles. The apostle Paul said “But even if we, or an angel from heaven, preach any other gospel to you than what we have preached to you, let him be accursed.” (Galatians 1:8) If any highly respected member of the church or even an angel tries to modify the teaching and practices of Christ, then they should be removed from the congregation.

Jude says this will happen in the last times, but according to John in his letters these who denied that Christ was the Son of God had already been part of the church and was trying to tear it apart with that belief which destroys the faith of man in Christ. Later there would be Mohammad who claimed an angel from God gave him the Koran. There would be Smith of the Church of Latter Day Saints who would claim his doctrine came from an angel. Paul said even if an apostle or angel taught what was contrary to Christ's teaching then they were accursed. Peter tells us to speak only as the word of God directs us, (1 Peter 4:11) not as directed by any other source.

Jude says these who are teaching false doctrines are doing this to satisfy their own earthly desires, they are not teaching because the Holy Spirit has inspired or directed them to teach these doctrines.

We have the scriptures which were inspired by the Holy Spirit, these are what we need to judge the teachings of man by. Do these teachings agree with what God gave us which was written by men who were inspired by the Holy Spirit.