mark 13:6 For many shall come in my name, saying, I am Christ; and shall deceive many. - Free Bible Online

      6. For many shall come in my name, saying, I am Christ--(see Mt 24:5) --"and the time draweth nigh" (Lu 21:8); that is, the time of the kingdom in its full splendor.
      and shall deceive many--"Go ye not therefore after them" (Lu 21:8). The reference here seems not to be to pretended Messiahs, deceiving those who rejected the claims of Jesus, of whom indeed there were plenty--for our Lord is addressing His own genuine disciples--but to persons pretending to be Jesus Himself, returned in glory to take possession of His kingdom. This gives peculiar force to the words, "Go ye not therefore after them."

JFB.