Stephen draws attention to a fascinating article by Morton Smith, “Notes on Goodspeed’s ‘Problems of New Testament Translation’,” JBL 64 (1945): 501-514 (which, incidentally, gives me the opportunity to mention for the first time, and belatedly, the fantastic new service to SBL members of the complete JBL back-catalogue at JSTOR). It's a cracking article, and on the case in point recommends the translation "So you say" "to preserve in English the ambiguity of the Greek, for it is only fair to the unlearned reader that the English text should present the same opportunities for misunderstanding as does the Greek". Stephen quotes the following segment from 308:
. . . The case of the answer to Pilate is exactly similar. For the Evangelists, of course, Jesus was a king. But when Pilate asks him if he is, they make him reply Σὺ λέγεις. And here their motive is clear, for, as John goes out of his way to explain, “Everyone that maketh himself a king speaketh against Caesar.” If, then, Jesus had openly claimed to be a king, in Pilate’s hearing, he would have been guilty of, and accordingly executed for, lèse-majesté. But all the Gospels are at pains to make clear that Pilate found Jesus innocent and had him executed only as a favor to the Jews. With the historical truth of this account we are not here concerned. The historical motive, which concerns us, is perfectly clear, for it was one of the principal fulfillments of prophecy, one of the main points of the apostolic preaching, that the Messiah, should be cast out and effectively killed by his own people. Σὺ λέγεις, therefore, in these passages, must be an ambiguous statement capable at least of being misunderstood by Pilate. . . .I think that there is another element to what is going on, though, and I am not sure about the statement that "For the Evangelists, of course, Jesus was a king." Well, yes and no. For Mark, Jesus was the Messiah, the one anointed, but what was he anointed to do or to be? Mark's answer is that he was anointed to suffer, to die, to be raised and to be exalted as Son of Man. I don't think he conceives of Jesus as a "king" during his life-time -- that would be a nonsense. His kingdom is in the future. Some of those present with him would not taste death before they had tasted it, but it was not here yet.
In other words, Mark is careful to distinguish between terms like "Messiah" and "King", one of which Jesus is willing to own if he can qualify it, and one of which he is not. The term "Messiah" is always and inevitably eschatological -- it points forward to a time in the future when Jesus will be acknowledged as king. He is anointed to rule, but he is not ruling yet; the kingdom is still in the future. I think that one of the reasons that we tend to miss this nuance is that we tend to make "Messiah" and "King" synonyms when they are not. David was an anointed one before he was a king, and Jesus is his son. This is where I find elements in Loren Rosson's post helpful, especially the reminder of the importance of distinguising between messiahs and kings, even if I am not sure how we would work out such issues in relation to the historical Jesus.
One of the remarkable things about Mark's Passion Narrative is that he does have repeated royal imagery, and the term "king" repeatedly occurs on the lips of his opponents. Is the crucifixion a kind of darkly ironic coronation -- is this when Jesus the Messiah becomes King, when his kingdom comes? I suspect that this is the right way to read Mark. Jesus is anointed to suffer and die and be raised, and only through that destiny does he finally become King -- but the full consummation comes when he returns as King.
But there is another element in the exchange with Pilate that is too easily missed if we focus just on "Messiah" and "King" terminology. Pilate asks Jesus if he is King of the Jews. But Mark's Jesus does not want to own that term since he is anointed not just to become a king of the Jews but also a king of all nations. Only consider the incident in the Temple, where in Mark the complaint is that the temple should be a house of prayer for all the nations (11.17).