For the sake of argument, I define “orthodox” in Islam as including the beliefs common to both the Sunni and Shi’a Muslims, though the Sunnis themselves say only they are orthodox (much like orthodox Christians may be defined as including much more than the denominations called “Orthodox”, including Catholics and most Protestants).

There are several issues in Islam I find contradictory and thus I would never become a Muslim, even if I were to ever believe in a god again.

1. Islam is said to be a world religion, appropriate for all peoples of the world to follow. This is absurd because Islam also makes Mecca the city that all Muslims must pray to five times a day and to make a pilgrimage to at least once in their lives. Islam also makes Arabic the default language for the Quran and for Muslim prayers and calls to prayer. Even Roman Catholicism no longer makes Latin the default language for Mass around the world. A truly worldly religion would have NO default language, no one city as the center of prayer and pilgrimage, and would see holiness in all places. We Unitarian Universalists might regard Boston as a place of historical significance to us, but we don’t pray to it!
2. Islam is said to be the final religion, the Quran is Allah’s final revelation and Muhammad the last of the Prophets.   This contradicts the idea of Allah as an all-knowing, all-powerful, and thus totally sovereign deity. If Allah wills another revelation by a new Prophet, as Baha’is have claimed, it is not for anyone to deny this. The argument that past revelations have been corrupted is pointless, since Islam is still divided into various sects. A truly pure and uncorrupted revelation from Allah would never have allowed this.
3. Islam condemns idolatry. Really? Then Muslims should stop regarding the Quran as the Word of Allah. Even official histories of Islam admit that it wasn’t put together until some years after Muhammad’s death. Why didn’t Muhammad himself do this? Also, walking seven times around the Kaaba in Mecca during pilgrimage looks too much like idolatry to me! It’s just a building! Also, see point 1 above.
4. Islam teaches that men can have no more than four wives at a time. Then why did Muhammad have nine or ten wives at the time of his death? Muslims should make up their minds; you cannot hold Muhammad as a supreme example of Muslims to follow and then ignore that he himself broke a basic rule of marriage!