The Christ (tou Cristou). The Messiah, of course, not Christ as a proper name of Jesus. Jesus here assumes that Psalms 110:1 ff. refers to the Messiah. By his pungent question about the Messiah as David's son and Lord he really touches the problem of his Person (his Deity and his Humanity). Probably the Pharisees had never faced that problem before. They were unable to answer.