Matthew 24:23

Lo, here is Christ - The Messiah. The Jews expected the Messiah to deliver them from Roman oppression. In the time of these great calamities they would anxiously look for him. Many would claim “to be” the Messiah. Many would follow those who set up that claim. Many would rejoice to believe that he was come, and would call on others, Christians with the rest, to follow them.

Believe it not - You have evidence that the Messiah has come, and you are not to be deceived by the plausible pretensions of others.