First of all, let me say that I do not claim to be an expert on comparative religion. But I am a product of the Walsh School of Contemporary Arab Studies and the Foreign Service Institute. I also spent most of my career in and around the Middle East. I'll offer a few thoughts.
A major "problem" with Islam is that while it has schisms, it has never gone through a reformation. Christianity went through a fairly violent one over a couple of hundred years as political, national, and cultural groups fueled sides. Judaism experienced a very quiet one.
To be a "good Christian," a believer has numerous options. He or she can choose the comfort of the rituals of Catholicism or the Episcopal church; or opt for the strict social conventions and guidance of the Southern Baptists; or perhaps the intellectual approach to God of the Presbyterians; and the emotional release of Evangelicalism. While these groups may disagree among themselves as to the "correct" way to properly worship God and lead a righteous life, there are no shortage of fellow believers to offer a community of shared belief among any of these.
Judaism is divided among orthodox and reform communities. Those more comfortable in the cultural traditions of the Jewish faith have orthodox synagogues and communities to support those traditional practices, while reform synagogues offer a far more liberal approach to worship and cultural requirements. While both can, and too often do, disagree vehemently with the practices of the other, the individual, like a Christian, has a number of options where he or she can find a community of like believers to be a "good Jew."
Islam has never had such a social transformation. To put it simply, one is either a "good" or "bad" Muslim. One either adheres to the strict cultural requirements around diet, prayer, fasting etc or one doesn't. Culturally, over the last century strict adherence to the requirements of Islam was often governed by economic and social standing. This is a generalization, but the better educated, traveled, and compensated one was, the less one was likely to strictly adhere to religious requirements. It is why many of us here have "normal" or Western interaction with many Muslims in this country or in Europe.
But there lies a two-fold trap.
First, are the options available to the sons and daughters of worldly families who suddenly decide to become "good" Muslims. Unlike, a rebellious child in a Western agnostic home who has numerous Christian religious options at hand, the Muslim youth is all too often left with only the radical choices that he or she finds on the internet. There have been numerous incidents of self-radicalization in West over the decades that led to violence and death. These individuals remain invisible and unidentifiable potential sleeper agents of terror.
Secondly, because of the impact of class, poorer and less well educated Muslims tends to be far more strict in their adherence to the strictures of Islam and their particular Islamic culture. Regrettably, with respect to the West, the migration of immigrants in recent decades has primarily come from these classes. Not only do these groups too often grimly hold onto traditions we in the West find appalling such honor killings and child brides, but they are also the groups most offended by western traditions and cultural norms. It is only surprising incidents like the horrific Yom Kippur attack in Manchester aren't more common.
Finally, Islam itself is confused with respect to its relationship with Christianity and Judaism. On the one hand all three great monotheistic religions embrace belief in the same God. Cultural norms between Orthodox Jews and Muslims are very similar and both worship what is essentially a common history as found in the Old Testament and Koran. At the same time Islam also embraces many of the traditions of the New Testament. Though Islam does not view Jesus as God or son of God, Islam does proclaim him the next greatest prophet after Mohammed. In Islam, salvation is open to Muslims, Jews, and Christians alike because all three communities are "People of the Book."
Yet, at the same time, there is still a powerful sense of "Jihad" - the desire to spread the new religion. This has both a purely religious context and a social one. Islam has the concept of "Dar el Islam" and "Dar el Harb." This loosely translates as the House or World of Islam, where Muslims are protected by their religion as expressed in Sharia Law, or the House or World of War where Muslims are not protected and Sharia Law is not yet enforced. This sets something of a precedent for behaviors, even resistance, to what Westerners would consider political, social, and governance norms.
Back to our second point these conflicts are most easily stirred among those less well educated classes - the very ones currently being embraced by the West. The chances of true assimilation seem very small to me.