“cried” indicates a loud shout, perhaps to a crowd which is withdrawing due to their falsely arrived at conclusions about the messiahship of Jesus. It could also indicate that Jesus spoke with a great deal of emotion. The major problem here is not their improper knowledge of Him or of His origins, but their lack of knowledge of God. He makes no attempt to refute the former, but dwells solely on the latter.

“In the statement ‘You do not know him,’ both pronouns are emphatic.  The inclusion of the separate form of the pronoun ‘you,’ which is expressed in Greek by the verb suffix, makes it emphatic; and ‘him’ is emphatic by reason of its position as the initial word in the clause.” [UBS]