Matthew 24:23-24

"Then" means "at that time," namely, at the end of the Tribulation (Matthew 24:2). Jesus warned the disciples about people who would claim that Messiah had returned toward the end of the Tribulation, before He really did return. People professing to be the Messiah and others claiming to be prophets will arise and mislead many people because of their ability to perform impressive miracles (cf. Matthew 24:11; Matthew 7:21-23; Matthew 16:1; Luke 17:23-24; Revelation 13:15). Evidently Satan will enable them to perform these signs and wonders.

"While false Christs and false prophets have always been in evidence, they will be especially prominent at the end of the age in Satan’s final attempt to turn people from faith in Christ." [Note: Walvoord, Matthew: . . ., p. 189.]

"If possible" (Gr. ei dynaton, Matthew 24:24) means the false prophets will hope to mislead the elect living in the Tribulation. It does not mean that the elect will inevitably remain true to the faith. Jesus had already said that some of His disciples would abandon the truth under persecution (Matthew 24:10-11; cf. Matthew 26:31). However the elect will not lose their salvation.