In his remarks during his remarkable series on the differences between Islam and Christianity's theories of Just War, our very own Tex wrote:
Islamic political theory on the other hand leaves little or no room for separation between temporal and spiritual authority, at least in the ideal Muslim community (umma). As mentioned earlier, unity is a key concept in Islam�specifically the unity of the believers. The umma is a single community that is separated from the rest of world by its identification as the people who are submitted to God; the umma are the believers mentioned in the Quran, the ones who obey God and look forward to receiving His blessings. The ideal Islamic society is one in which all men are willingly submitted to God.
While Tex limited his analysis of the effects of this unification of the temporal and eternal to the possibility--or lack thereof--of an Islamic Just War theory, Efraim Karsh takes it one step further, arguing that imperialism is intrinsically related to Islamic theology:
This unique fusion of religious and temporal authority, established by the Constitution of Medina, sowed the seeds of Islam's millenarian imperial experience. Muhammad was, of course, not the first political leader to have associated himself with divine guidance. Numerous rulers of all hues had done this before. Yet in pagan societies the authority of gods was limited to specific territories and/or functions, and it was generally accepted that there could be other deities in other places. The authority of Allah, as embodied in the person of His Messenger, was all-encompassing and left no room whatsoever for other gods. This made the worldwide expansion of the umma, as both the constituency in which Allah's authority had been established and the tool for its further dissemination, only a question of time. For if Allah is one and His Messenger is one and the two are fundamentally indivisible, then all humanity should believe in the one and only true religion--Islam--and be organized in one universal community living by its laws.
Karsh's thesis is doubtlessly contentious, and while it may be true historically, there are those who argue forcefully that Islam is perfectly compatible with a non-imperialist secular democracy. From the vantage point of comparative political theology, the Cross, the Resurrection, and perhaps most importantly here, the Ascension are central for delineating Christian models of political engagement from Islamic.