The Islam of the “moderate Muslim” as described by most western liberals sounds like a great religion, one that is vastly superior to Christianity or Judaism. The truth, however, is that Moderate Islam doesn’t exist and Moderate Muslims are mostly apostatizing.
In Christianity, starting in the 16th century, there was a Reformation that made Protestant Christianity a personal religion, based on an individual’s personal relationship with god and his personal reading of scripture. Over time, this took on many variations and the pluralism that created led to the notion of religious toleration and then religious freedom. Protestantism’s general distrust of authority and its pluralism led to the separation of church and state, which ultimately led to the liberalization of both church and state.
Even Catholicism eventually was sucked into modernity by the competition from Protestantism. However, even today, Catholicism is more like Islam in that Church doctrine hasn’t changed so much as most of its followers simply ignore its teachings. In Western countries, over 90% of Catholics disagree with the Church about birth control, for example.
In Judaism, the situation is similar. The Jews remained in a medieval timewarp until the Jewish Enlightenment, or Haskala, starting in the late 18th century. Immediately thereafter, Haskala theologians essentially created a Protestant version of Judaism, which eventually led to the liberal streams, to which the vast majority of American Jews belong. In other places, most are either Orthodox or secular.
The main distinction to be made between the Islamic world and that of Christians and Jews is that the latter two have a way to be religious—devout, even—without subscribing to a medieval or quasi-medieval version of the faith. This isn’t to say that some don’t choose the latter; they do. But when there is no moderate version of the faith to speak of, then anyone drawn into a more religious life is drawn towards the older ways.
Certainly, this doesn’t mean that everyone drawn towards Muslim spirituality becomes a terrorist, but it does mean that, for example, they won’t be likely to have modern attitudes towards women, gays, or other western behavior.