One of the reasons that we attacked Iraq first was that it already appeared very secularized (Saddam occasionally dressed up like Saladin, but that was about it - the mullahs weren’t running things) and Bush thought that people would adapt more easily.
However, he underestimated Islamic lunacy. If we had imposed a very rigid system for awhile, a few years, and not let them enshrine Islam in their constitution, there might have been hope. But we handled it all the wrong way, IMHO (dealing with Mookie, etc.).