Like, Jesus never had a country to run, but Muhammad did almost from the beginning, and in addition to being an important prophet, he was a good general. And in 630, the Islamic community took back Mecca. They destroyed all those idols in the Kaaba, and soon Islam was as powerful a political force in the region as it was a religious one. And it's because the political and religious coexisted from the beginning that there's no separate tradition of civic and religious law like there is in Christianity and Judaism. So then when Muhammad died in 632 CE, there wasn't a religious vacuum left behind. Muhammad was the final prophet, the revelation of the Quran would continue to guide the ummah throughout their lives. But the community did need a political leader, a caliph, and the first caliph was Abu Bakr, Muhammad's father-in-law, who was not without his opponents.