Jude 1:16–19 (ESV)

16 These are grumblers, malcontents, following their own sinful desires; they are loud-mouthed boasters, showing favoritism to gain advantage.

One of the reasons for caution is the fact that false teachers do not have the Spirit of God. They are worldly people who know nothing except their own desires, so do not listen to them.

Up until this point all of Jude’s quotations and allusions have come from either the Old Testament or some other book that was written before the coming of Christ. Now in Jude 1:17–18 he shares a prophecy that came from the apostles: In the last time there will be scoffers, following their own ungodly passions.

If you are surprised by the number of false teachers in churches around your country and the rest of the world, well you should not be. It is exactly what the apostles predicted. The last days, which is the time in which we are living—the time between Christ’s ascension and his return—will be marked by many people seeking to change God’s Word in order to indulge their desires. And they will do so because they do not have the Spirit.

Now the exact reason why an unbeliever would seek to be part of God’s church—never mind becoming teachers within it—is unclear. Perhaps they think the church community is a place where they can find money or win the approval of men. Having a crowd of people who come to you for advice and listen to your teaching will certainly appeal to some. Maybe it is also a case of wanting the benefits of the gospel, the promise of life after death, but not the cost. Whatever their motives, these people are in reality nothing less than unbelievers. They are not born again, they have not been adopted as children, the love of God has not transformed their hearts. And so even if they are likeable people, even if their words sound impressive, even if they should confess the Apostles’ Creed, they are not promoting the cause of Christ. No one who changes the Bible to excuse sin is promoting the cause of Christ.