John Gill Commentary Mark 15:32

"Let the Christ, the King of Israel, now come down from the cross, that we may see and believe. And they that were crucified with him reproached him." — Mark 15:32 (ASV)

Let Christ the king of Israel
Who sets up for the Messiah, and whose followers call him the king of Israel, whom the nation expected: and if he is so, let him

descend now from the cross, that we may see ;
see him come down, and be eyewitnesses of his power:

and believe ;
that he is the Messiah that was prophesied of, and has been waiting for:

and they that were crucified with him reviled him ;
that is, the thieves, at least one of them; (See Gill on Matthew 27:44).