From the destruction of the Temple to anti-Semitism
Written by Stephen Langfur
Except where noted, what follows is the summary of an argument made by historian Martin Goodman in his Rome and Jerusalem:  

An emperor had to beware of a successful general: the general could lead his army to Rome and dethrone him. In 66 AD, the emperor Nero chose Vespasian to quell the Jewish revolt because he was a "competent mediocrity" with no aristocratic background, so he would not be a threat. In 68, however, faced by rebelling commanders and the loss of the grain supply from Egypt, Nero committed suicide. One general after another, three in all, seized the throne and lost it. Finally, Vespasian's army acclaimed him emperor in 69, but he needed a major victory as a basis, and the only arena of battle at the time was Judaea. What had started as a punitive action now took on a bigger importance. While in Egypt and preparing to go to Rome, Vespasian ordered his son Titus to conquer Jerusalem quickly, no matter what the cost, and Titus did so, losing many soldiers. In the fracas, the Temple was burned (the deed of a soldier with a torch, probably against Titus' intentions).

Vespasian and Titus, the Flavians, had to make maximum PR out of their victory, for it would serve as the basis for their claim to power. They celebrated a great triumph in Rome (crowned by the famous Arch of Titus that we see today), and they painted the victory as a major accomplishment over a "wicked race" (Seneca). For this reason they did not allow the rebuilding of the Temple, as would normally be expected.

Arch of Titus: sack_of_jerusalem

Vespasian even compelled the Jews empire-wide to pay a tax for support of Jupiter's temple in Rome, replacing the tax they had paid for their Temple in Jerusalem. Titus succeeded Vespasian but soon died, and his brother Domitian took over. This Flavian's initial claim to fame was limited to his participation in Titus' triumph years before, and so he continued the anti-Jewish policy until his assassination in 96. The next emperor, the non-Flavian Nerva, relaxed the Jupiter tax, but he died of natural causes a year later, having adopted a commander named Trajan as successor. Although a commander, Trajan had no clear military claim to prominence; he  depended on the fame of his father, who had commanded the crucial Tenth Legion during the Jewish revolt. Therefore, the importance of the victory over the Jews was again emphasized, and the Jupiter tax renewed.

In 115 AD, Trajan campaigned against Parthia, which had been tolerant toward the Jews in Mesopotamia (descendants of the exiles to Babylon). While the emperor was in the East, the Jews of the Mediterranean Diaspora rose in revolt (we do not know exactly why, because no contemporaneous texts about the Jews have been preserved). Perhaps they were responding to a distress call from their co-religionists in Mesopotamia, whom the conquering Romans were ruthlessly expelling. All indications are that the Diaspora Revolt was devastating for the provinces of Libya and Egypt; it spurred anti-Jewish feeling throughout the empire.

HadrianWhen Hadrian became emperor in 117, he gave up Trajan's conquests, pulling back from Parthia and Armenia in order to focus on political problems in Rome. As a result, perhaps, the Diaspora Revolt subsided. A decade followed without anti-Jewish measures, and the Jews may have renewed their hopes for rebuilding the Temple. It seems, however, that Hadrian was merely biding time, dealing with the provinces one by one. On a visit to Judaea in 130 AD, he decided to erect a Roman colony on the site of the erstwhile Jerusalem, naming it Aelia Capitolina (Aelia for himself, Capitolina for Jupiter Capitolinus). The move was probably meant to put an end to Jewish hopes and hence to any further disturbances. "Leaving the site of Jerusalem empty for sixty years had proven an invitation to the Jews to agitate for a return to their former glories. To expect Rome to disband a Roman colony would be so obviously ridiculous that agitation would evaporate" (Goodman, p. 485). The effect was quite the opposite. In the words of the historian Cassius Dio: "This brought on a war of no slight importance" (Cassius Dio 69.12.1). 

It is remarkable that the Jews of Judaea would again challenge Rome, especially in 132 AD, when no other wars were underway that might have drawn off the full brunt of Roman might. Perhaps they interpreted Hadrian's unilateral withdrawal from Parthia and Armenia as a sign of weakness, thinking they could make their land into a "hot potato" and gain the same liberation. But part of the explanation, surely, resides in the fact that the Jews placed their hopes in God, not in "facts on the ground." Although Goodman does not emphasize apocalyptic eschatology, it runs throughout the history. (For its part in the first revolt, see here.) Its importance in the revolt of 132 AD is personified in the leader, Shimon Bar Kosiba, nicknamed Bar Kokhba, meaning "son of a star," from the prophetic verse of Balaam, "a star will come out of Jacob" (Numbers 24:17). His great contemporary, Rabbi Akiba, quoted this verse in relation to him, adding, "This is the King Messiah." Another rabbi retorted, "Akiba, grass will grow in your jawbones, and he still won't have come." After the failure of the revolt, the rabbis tended to call Shimon "Bar Koziba," "son of the lie."

According to Cassius Dio (69.12,13), the Jews prepared this third major revolt with care, digging underground passages in Judaea from which they could spring to attack the Romans, who—if they tried to pursue them with armor back into the holes—would be trapped like Winnie the Pooh. (We can crawl through some of these caves today in the Shephelah; the best are at Khirbet Midras.) Engaged in weapons manufacture for the Romans, the Jews deliberately botched some; they then took the rejected weapons and repaired them. In 132 they attacked, at first with great success. It is thought that they may have wiped out a legion. But against the Roman army of that time, nothing failed like success. Given the peace elsewhere, Hadrian was able to concentrate his forces on Judaea. The underground passages were of little help when the Romans besieged the towns containing the rebels' women and children.

The victors had been badly hurt, however. In writing to the Senate when it was over in 135 or 136, Hadrian could not employ the usual formula: "I and the legions are in health." He celebrated no triumph. From this time forth, where the Romans were concerned, the negative connotation of "Jew" would be irreversible. The Jews were banned from Aelia (and would remain banned through the Byzantine period, when it was called Jerusalem again). Circumcision was forbidden in Judaea. In fact the name of the province was changed to "Syria Palaestina," honoring Israel's old enemy, the Philistines. Such a name change was unprecedented in the empire: "Only the Iudaei ceased to have a homeland because of what they had done" (Goodman), p. 494). "Many, perhaps most, of those Jews who survived in the new province of Syria Palaestina must have reacted to the defeat of Bar Kokhba by ceasing to think of themselves as Jews" (ibid., p. 501).  

For a hundred years after the end of the revolt, all emperors derived their authority in one way or another from Hadrian; the view of Judaism as a dangerous cult became entrenched. On the development into later Christian anti-Semitism, Goodman (p. 583) is specific:

"[T]o gain credibility in the Roman world after 70 [i.e. after the destruction of the Temple – SL] Christians needed not only to deny their own Jewishness but to attack Judaism altogether. It would have been quite possible for early Christians to have maintained a view of Judaism as another, older, relationship with God, as Paul had sometimes done, and as has become more common, too, among modern Christian theologians. But if Christians were to defend their own good name and seek converts in a Roman world in which, after 70, the name of the Jews excited opprobrium, it was easier to join in the attack and agree with the pagans that the defeat of the Jews and the destruction of the Temple were to be celebrated as the will of God."