Political leaders in the Roman Empire were also public cult leaders. Roman religion revolved around public ceremonies and sacrifices; personal belief was not as central an element as it is in many modern faiths. Thus while the private beliefs of Christians may have been largely immaterial to many Roman elites, this public religious practice was in their estimation critical to the social and political well-being of both the local community and the empire as a whole. Honoring tradition in the right way – "pietas" – was key to stability and success. Hence the Romans protected the integrity of cults practiced by communities under their rule, seeing it as inherently correct to honor one's ancestral traditions; for this reason the Romans for a long time tolerated the highly exclusive Jewish sect, even though some Romans despised it. Historian H. H. Ben-Sasson has proposed that the "Crisis under Caligula" (37-41) was the "first open break" between Rome and the Jews. After the First Jewish–Roman War (66-73), Jews were officially allowed to practice their religion as long as they paid the Jewish tax. There is debate among historians over whether the Roman government simply saw Christians as a sect of Judaism prior to Nerva's modification of the tax in 96. From then on, practicing Jews paid the tax while Christians did not, providing hard evidence of an official distinction. Part of the Roman disdain for Christianity, then, arose in large part from the sense that it was bad for society. In the 3rd century, the Neoplatonist philosopher Porphyry wrote: