What does 2 John 1:8 mean?

The warning against false teachers was to "watch yourselves." When believers encounter a false teacher, in this case one who denies Christ's humanity, they are not to be concerned with the false teacher's life or arguments. Instead, a Christian is to guard against those false teachings in their own lives. A believer's primary concern is their own spiritual life.

The reason believers are to watch themselves when false teachers are near is also mentioned. Listening to a false teacher cannot cause a believer to lose his or her salvation, but can cause them to lose spiritual rewards. Why? Because a deceived believer does not faithfully serve the Lord. He or she then loses out on possible heavenly treasures. The power of salvation is not simply gaining heaven and avoiding hell. It also means having the ability to live a righteous and godly life—but this is a power Christians can fail to take advantage of.

John includes himself in this warning by stating "we." Even this great apostle had to guard against false teachers and their teachings.