Historian Mark R. Cohen proposes a comparative approach to understanding Jewish life under Islamic rule, noting that Jews in Islamic lands often experienced less physical violence than Jews under Western Christendom. He posits that Muslims considered Jews less theologically threatening than Christians did, suggesting that the Christians wanted to establish a separate religious identity from Judaism, from which their faith split and diverged. According to him, instances of persecution were occasional, more the exception than the rule, and claims of systemic persecution at the hands of Muslim rulers are myths created to bolster political propaganda. The situation where Jews in the Muslim world both enjoyed cultural and economic prosperity at times, but were widely persecuted there at other times, was summarised by G. E. Von Grunebaum: