Luke 20:44

πῶς αὐτοῦ υἱός ἐστιν; To a Jew it was inconceivable that a father, or ancestor, should call his son “Lord.” The only possible solution—that the Messiah was only “made of the seed of David after the flesh” (Romans 1:3) was one which they had never chosen to accept. They, like the Ebionites, expected for their Messiah a mere ‘beloved man.’ And thus, for the second time on this day, they had drawn on their own heads the humiliating necessity of publicly confessing their ignorance. They ‘did not know’ whether the Baptist was an Impostor or a Prophet; they ‘could not answer a word’ to a most obvious question as to the Messianic hope which they put forward as the very centre of their religion! Comp. Luke 14:6.