“For you, brothers, became imitators of God’s churches in Judea, which are in Christ Jesus: You suffered from your own countrymen the same things those churches suffered from the Jews, 15 who killed the Lord Jesus and the prophets and also drove us out. They displease God and are hostile to all men 16 in their effort to keep us from speaking to the Gentiles so that they may be saved. In this way they always heap up their sins to the limit. The wrath of God has come upon them at last.

The PASSAGE ITSELF is CERTAINLY not 'anti-semitic!

First, it is written by a Jew (Paul/Saul), who loved his people dearly (cf. Roman 9.1ff). and who HIMSELF had participated in persecuting Jewish believers in the Messiah! Compare his words in Romans 9:

“I am telling the truth in Christ, I am not lying, my conscience bearing me witness in the Holy Spirit, that I have great sorrow and unceasing grief in my heart. For I could wish that I myself were accursed, separated from Christ for the sake of my brethren, my kinsmen according to the flesh, who are Israelites, to whom belongs the adoption as sons and the glory and the covenants and the giving of the Law and the temple service and the promises, whose are the fathers, and from whom is the Christ according to the flesh, who is over all, God blessed forever. Amen.”

Second, it points out that Gentile opposition to the Gospel is JUST LIKE Judean opposition to the Gospel (i.e., Gentiles are guilty of the same persecution of believers as are the Judean opponents)--hardly a justification for anti-semitism (unless it also justifies anti-thessalonianism)

Third, the really strong condemnation by Paul is about a VERY SMALL SUBSET of Jewish people--the Judean/Jerusalem LEADERSHIP who were part of the Jewish-Roman condemnation/crucifixion process. This would exclude all the Jewish leadership which was NOT supportive of the crucifixion (e.g., Nicodemus, Joseph of Arimathea, etc), the common Jewish people of Jerusalem, ALL the other Jewish people in Judea/Galilee, all the thousands of Levitical priests who became believers, and ALL the dispersed Jews. None of these groups had ANYTHING TO DO with the crucifixion. (And, obviously, any 'anti-semitism' THEORETICALLY based on this passage should be confined to ONLY THAT TINY group of 1st century Jerusalem leadership!)

Fourth, the Jewish writers before Saul/Paul already admitted that the First-Temple Jewish leadership 'killed the prophets' (Jesus was just the 'next in line'): Nehemiah 9.5,26 has the Levites confessing:

“Then the Levites, Jeshua, Kadmiel, Bani, Hashabneiah, Sherebiah, Hodiah, Shebaniah, and Pethahiah, said, “Arise, bless the Lord your God forever and ever!...But they became disobedient and rebelled against Thee, and cast Thy law behind their backs and killed Thy prophets who had admonished them so that they might return to Thee, and they committed great blasphemies.” (NASB)

Fifth, David Stern's Jewish New Testament Commentary actually argues that this passage is to COUNTER POSSIBLE ANTI-SEMITISM (i.e., that God would do any 'judging' HIMSELF):

"But God's fury will catch up with them in the end. I don't consider this or Paul's lengthier discussion at 2 Th 1:6-9. to be vindictiveness. On the contrary, I take it to be a way of countering the possible vindictiveness of his readers toward their persecutors, along the lines of Romans 12:19, where, quoting the Tanakh on the subject, he advises believers not to exercise vengeance themselves but to leave such matters to God. "

Sixth, I have to agree with Stern here: there is absolutely NOTHING in this text that authorizes ANYONE to treat Jewish people other than with love! There is no command to judge them, to abuse them, to do ANYTHING to them--the passage is simply explaining the cause of a historical persecution. To move from this text to ANYTHING like persecution, anti-semitism, or vengeance is out of step with the instructions of Jesus and Paul toward adversaries ("bless those who curse you, do good to those who persecute you"!); and totally unwarranted by the text.

Seventh, the 'opposing all mankind' by hindering the gospel is in line with Jesus' condemnation of hypocritical Torah-teachers: "You are shutting the Kingdom of Heaven in people's faces, neither entering yourselves nor allowing those who wish to enter to do so", Matthew 23:13...this is also a very historically short-lived issue. The Jerusalem elite stopped fighting the mission to the Gentiles shortly after the two groups diverged, in the late first century. This accusation could ONLY apply to a small subset of Jewish people, and not to the ethnicity as a whole.