So, this is supposed to “challenge the uniqueness of my theology?” A broken tablet with faded Hebrew writing on it which is purported to speak of a messiah who was to be raised after three days:

The slaying of Simon, or any case of the suffering messiah, is seen as a necessary step toward national salvation, he says, pointing to lines 19 through 21 of the tablet — “In three days you will know that evil will be defeated by justice” — and other lines that speak of blood and slaughter as pathways to justice.

To make his case about the importance of the stone, Knohl focuses especially on line 80, which begins clearly with the words “L’shloshet yamin,” meaning “in three days.” The next word of the line was deemed partially illegible by Yardeni and Elitzur, but Knohl, who is an expert on the language of the Bible and Talmud, says the word is “hayeh,” or “live” in the imperative. It has an unusual spelling, but it is one in keeping with the era.
Two more hard-to-read words come later, and Knohl said he believed that he had deciphered them as well, so that the line reads, “In three days you shall live, I, Gabriel, command you.”
To whom is the archangel speaking? The next line says “Sar hasarin,” or prince of princes. Since the Book of Daniel, one of the primary sources for the Gabriel text, speaks of Gabriel and of “a prince of princes,” Knohl contends that the stone’s writings are about the death of a leader of the Jews who will be resurrected in three days.
He says further that such a suffering messiah is very different from the traditional Jewish image of the messiah as a triumphal, powerful descendant of King David.
[…]
Regarding Knohl’s thesis, Bar-Asher is also respectful but cautious. “There is one problem,” he said. “In crucial places of the text there is lack of text. I understand Knohl’s tendency to find there keys to the pre-Christian period, but in two to three crucial lines of text there are a lot of missing words.”

I think these scholars need to ask themselves if they did not know the story of Jesus, would they be making the same assumptions about the missing text that they are making. It seems that they are being too quick to fill in the missing blanks with what they think it should say based on Christ’s resurrection.
That Knohl had a bias might be seen from his previous publication:

If Knohl’s interpretation of “Gabriel’s Revelation” is correct, it would lend evidence to his previous theories, published in his 2002 book, “The Messiah before Jesus.” Knohl is one of several scholars who suggest Jesus may not have been unique in his claim to face suffering, death and resurrection, but that sources, like this tablet, suggest a common messianic story that New Testament writers may have merely been copying.
“This should shake our basic view of Christianity,” Knohl told the Tribune. “Resurrection after three days becomes a motif developed before Jesus, which runs contrary to nearly all scholarship. What happens in the New Testament was adopted by Jesus and his followers based on an earlier messiah story.”

Kind of makes a leap there from the text (an excerpt of Knohl’s article can be found here) to suffering, death and resurrection which isn’t evident in the text he quotes which is “by three days live, I Gabriel, command you, prince of princes.” And that quote is based on his assessment of partial words. Not enough there to suggest that the disciples of Jesus based their account on messianic stories that may have circulated at the time. Too many leaps to be believable. So much for shaking our view of Christianity.
And then there’s this:

“His mission is that he has to be put to death by the Romans to suffer so his blood will be the sign for redemption to come,” Knohl said. “This is the sign of the son of Joseph. This is the conscious view of Jesus himself. This gives the Last Supper an absolutely different meaning. To shed blood is not for the sins of people but to bring redemption to Israel.”

Um…the two are not mutually exclusive:

ESV Matthew 1:21 She will bear a son, and you shall call his name Jesus, for he will save his people from their sins.”

ESV Luke 1:68 “Blessed be the Lord God of Israel, for he has visited and redeemed his people 69 and has raised up a horn of salvation for us in the house of his servant David, 70 as he spoke by the mouth of his holy prophets from of old, 71 that we should be saved from our enemies and from the hand of all who hate us; 72 to show the mercy promised to our fathers and to remember his holy covenant, 73 the oath that he swore to our father Abraham, to grant us 74 that we, being delivered from the hand of our enemies, might serve him without fear, 75 in holiness and righteousness before him all our days.

Jesus did come to bring redemption to the nation of Israel by saving them from their sin, the Bible’s pretty clear about that.