From Chapter 16: Islam and Sufism
When in the 7th century Mohammed enunciated his creed, he did so to a society existing in a state of primitive consciousness; and one whose environment -- sunscorched, storm-wracked, and unproductive -- was an arduous one. The people who wandered over this land were a savage people united only by tribal alliance, and had no highly-developed system of ethics, social integration, or cultural expression. Mohammed understood them thoroughly, adapted his religion accordingly, and in the space of his lifetime united and transformed these vagrant peoples into an empire, chiefly by forcing them to accept a common loyalty not to the tribe or an individual, but to a national religious community. This was a nation in the Jewish sense of a group of people, rather than of a group of people in a specific geographical area. The transformation was unique; the only empire in history to be totally rooted in a religion. In Islam religion created an empire; in Christianity, an empire adopted a faith and called itself The Holy Roman Empire, which, as the old saw goes, was neither holy, nor Roman, nor an empire. Whether led by Arabs, Persians, or in later times the Turks, Islam remained essentially all three, a portable theocratic state, much of whose impetus came from the fact that it was portable.
"a portable theocratic state"
Can anyone better define Islam in four words?