In the 1992 Genesis single Jesus He Knows Me, Phil Collins portrays a US television evangelist who’s motivated by money and not by God. The lyrics include:

Won’t find me practisin’ what I’m preachin’
Won’t find me makin’ no sacrifice
But I can get you a pocketful of miracles
If you promise to be good, try to be nice
God will take good care of you
Well, just do as I say, don’t do as I do

And the topic of fake preachers is not a modern phenomenon.

The book of Jude is a round-robin letter from the half-brother of Jesus sent to churches taking aim at false teachers. These itinerant prophets claimed to be filled of the Holy Spirit, but in fact were living lives of depravity. 

The New Testament scholar Richard Bauckham said that Jude’s language “suggests that the troublemakers were itinerant prophets of teachers, perhaps with a group of followers. Such wandering teachers were a feature of early Christianity, as of the contemporary religious world in general, and frequently occur in early Christian literature as the cause of trouble in the churches”.

Here are three key points from the letter.

1. Grace isn’t a licence to sin

Those fake teachers are carrying on doing whatever they like, instead of repenting.

Jude writes (NIV):

For certain individuals whose condemnation was written about long ago have secretly slipped in among you. They are ungodly people, who pervert the grace of our God into a license for immorality and deny Jesus Christ our only Sovereign and Lord.

Salvation in Christianity is by grace, not works. But behaviour change is a logical consequence of following Jesus, and grace is not a “get out of jail free” card that lets people sin however they like.

2. Fake teachers are only interested in themselves

Like the prosperity gospel preacher in the Genesis song, the fake preachers Jude talks about are only interest in themselves. Jude writes:

These people are blemishes at your love feasts, eating with you without the slightest qualm – shepherds who feed only themselves.

3. Salvation requires perseverance

Jude points to Old Testament warnings about people and angels who might have thought they might have been doing well – but weren’t. He writes:

Though you already know all this, I want to remind you that the Lord at one time delivered his people out of Egypt, but later destroyed those who did not believe. And the angels who did not keep their positions of authority but abandoned their proper dwelling – these he has kept in darkness, bound with everlasting chains for judgment on the great Day.

Later in the chapter, Jude talks about the importance of keeping in God’s love – of persevering. He writes:

But you, dear friends, by building yourselves up in your most holy faith and praying in the Holy Spirit, keep yourselves in God’s love as you wait for the mercy of our Lord Jesus Christ to bring you to eternal life.

There are people out there who have, previously, taken Christianity seriously. But as life got more difficult, and as their doubts grew, they remained interested in the structures and culture of the church – but did not continue in a genuine relationship with God. But Jude says we need keep building ourselves up in our faith.