Remember that both Roman Catholicism as well Lutheranism share the supersessionism: supersessionism affirms that God declared no more existing the covenant(s) with Israel after the crucifixion of Jesus the Lord and at the opposite that God damned the Jews.
This means that for Roman Catholicism and Lutheranism the Jews who acclaimed Barabba in the square were the representatives of the true old Covenant and the rest of the Jews who never attacked Jesus were not. From here the necessity for Rome and her supersessionist allies like Luther to multiply (especially virtually with anti-Jewish propaganda) the "bad Jew" and to suppress the "good Jew" in history. Because the existence of a "bad Jew" supports the reason of existence of the supersessionism.
Problem, reaction, solution.
Supersessionism is dictated by the necessity of the post-Flood Cushites and their heirs to steal the Covenant from the Jews and to declare that 'God' made a new Covenant with them. For this reason Satan created the Roman Empire just little before the birth of Jesus Christ, in order to prevent His birth and therefore the underlined true universal importance of the Covenants of God with the children of Israel which was the not avoidable premises for the birth of the Saviour, the Son of God, Jesus the Lord.
Ancient Roman Empire was therefore built "just in time" in order to prevent what announced at the beginning of the world, the birth of the Saviour:
".......And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel...........". [Genesis 3:15 KJV]
It was Herod who tempted to kill the baby Jesus, but in doing this he would have deepened the reason of existence of the Jesus' Gospel. But it was the Ancient Rome to have the duty to contrast spiritually the seed, to try to spiritually kill Him, a more important task.
The reason of existence of anncient Rome was the spreading of paganism (= satanism under phylosophical, artistic aestetic mask) in order to deprave, corrupt, degenerate and pervert the greatest number of people in the world. Paganism was - as exposed by Alexander Hislop - the conscious vaccine against the God's Word. Paganism was and is reversing the significance of the God's Word. The creators of paganism at the Babel tower (the Cushites) were inspired by the obsession against the oral tradition of the Noah's descendents and wanted to re-write the divine Words but finely turning them against God the same. Making to appear God as the 'villain' and the Snake (Satan) as the 'benefactor' of humanity: this is the true and only obsessive goal and purpose of paganism/heathenism [[see various Chicks publications' books on the theme].
Therefore the presence of Jews in ancient Imperial Rome and as well in Roman Catholic establishment were and are perfectly logical: with such Jewish presences of traitor Jews, Satan obtained the formal act of disclaimer of the old Covenants signed by formally true Jews, in order to declare void any previous Covenant of God with the Children of Israel, previous old Covenant which prepared the path for the coming of the Seed.
The idea of the Cushites of Imperial before and Catholic then Rome was and is to 'force' God to sign a new Covenent with the ancient enemies of God, the spiritual descendants of Ham, Cush and Nimrod. But they know that it is impossible to force God to anything, therefore they smuggle what is a Covenant (of ancient imperial Rome and later Roman Catholic church) with Satan under the supersessionism, i.e. the "new Covenant of God with Rome", being Rome the "New Jerusalem".
It is therefore logical and consequent the use of Jews inside the social life of Middle Age, and in the same church of Rome, as with their presence Rome is only feeding the interests for a "church" to "defend" against the "enemies of the new Covenant" (the Jews who didnt get rid of the old Covenant), and therefore is a way to drag attention and support on the satanic Vatican but more to justify the necessity of the "new Covenant", officially "with God", truly with the Snake (Satan). Therefore from Joseph Flavius to that Jewish pope and the Rotschilds, there's only the work of Satan in order to destroy the actual significance of the Old Covenants in order to legitimate a "new Covenant" but with Satan to destroy both the Children of Israel as well the Christians.