What does Mark 13:22 mean?

This verse applies to just about every moment from Jesus' ascension until the day Jesus returns. Simon bar Kokhba, who died in AD 135, was thought by his followers to be the Jewish Messiah. Sun Myung Moon claimed to be the Messiah and fooled millions of members of his Unification Church. Jose Luis de Jesus Miranda of Growing in Grace International claimed to be both Jesus and the Antichrist. Jim Jones said he was Gandhi, Buddha, Vladimir Lenin, and Jesus reincarnated, and over nine hundred people believed him enough to poison themselves.

The last part of this verse has been misinterpreted to say that false teachers will convince Christians that they are Jesus, and the Christians will lose their salvation. What the verse actually means is that these false Christs will be so convincing that believers would be deceived if not for the truth Jesus places in their hearts.

A believer may be deceived in some aspects of theology, and indeed, no one on earth can know God fully, but believers will never be deceived regarding the essential tenets of their salvation. Jesus will not dismiss us (John 6:37). Jesus will "sustain us to the end" (1 Corinthians 1:8). We will be "kept blameless at the coming of our Lord Jesus Christ" (1 Thessalonians 5:23). In matters of salvation, Christians will not follow the voice of another (John 10:5). True believers won't follow a person who "pretends" to be Jesus.

In the end times, the Antichrist will sit in the temple and claim to be God. Now, the Holy Spirit restrains such strong displays of blasphemy (2 Thessalonians 2:6–7), but during the tribulation, the Holy Spirit will confuse the minds of those who reject Jesus and follow the Antichrist so that they do believe the Antichrist is God (2 Thessalonians 2:1–12). For those of us who understand this now, our work is to teach others the truth about Christ so they can discern truth from deception (Mark 13:23).