As with Easter and Passover, the birthday of the Prophet Muhammad is dated by the lunar calendar. This year it falls on Feb. 15, and the time seems particularly fraught with meaning. Every time there is a crisis in the Muslim world, grudges and resentments going back almost to the beginning of the faith, in the seventh century, seem to resurface. Islam, being an all-inclusive religion, refers every aspect of life back to God. When you feel that God has been affronted or disobeyed by your enemies, time disappears. It's always a good time to reopen old wounds. That's why there are rarely any upsets in society that are not also religious upsets. Traditional Muslim society equates with religious society. In Egypt, where secular rule has been the rule, the chemistry between God and government is still volatile and almost impossible to fathom if you live outside the Arab world. I don't speak as an insider but as a writer who delved into these issues when researching a book on the life of Muhammad. It is remarkable the extent to which the life of the Prophet set the template for attitudes that persist today. Among the most marked of these are a sense of being embattled for God, a defensive posture against infidels, a fierce desire to devote one's life to protect the Prophet, a desire to obey God's laws down to the smallest letter, and jihad, which in its broadest meaning denotes the struggle of the soul to reach a pure relationship with Allah against the temptations of one's base nature. These elements are entangled inside the worldview of devout Muslims. The new guard that tries to provoke change must contend not just with the old guard -- in this case the clash is between the youth of Egypt and the ruling military elite -- but also there is the rear guard of religious conservatism. A centuries-old worldview is always ready to condemn change as being against the will of God. What I came to understand is that this worldview has its reasons for being. The Prophet was personally troubled about the messages he received that commanded him to convert the entire world to the new faith. When the early Muslims first fled from Mecca to Medina, Muhammad was welcomed as a peacemaker among warring tribes and faiths. His approach was conciliatory, and all sides recognized him as a fair arbiter. Islam sees itself as a faith that is far more inclusive than exclusive. Therefore, when Muhammad was forced to lead battles in defense of the faith, and afterwards when he turned on former Christian and Jewish allies, a dangerous rift became part of the Muslim worldview, at once aiming for universal peace and brotherhood but using violent means to get there. Christianity has its own built-in contradictions. This will always occur as long as human nature is divided. "What we say" and "what we do" have been perpetually at odds. In the present crisis the U.S. also falls between two stools. We say that we promote democracy around the world, but what we do is to defend stability (and the steady stream of Gulf oil) in support of reactionary, oppressive regimes. The layer of contradiction that we don't have, for the most part, is the religious one. Lurching toward modern secularism, Iraq, Iran, and Bosnia all ran afoul of religious pressures, and each society had to make peace with itself -- a very fragile peace at best -- in its own way. No doubt the same will happen in Egypt, with whatever convulsions that ensue when people are forced by passion and raging events to examine their innermost beliefs.