Most in the West have little understanding that this 'problem' has been ongoing--waxing and waning--for almost 1400 years.
The confusion stems from our understanding of morality. Even atheists in our Western cultures generally agree to certain norms of behavior and we expect that all other cultures share these norms. We expect these 'facts' at our own peril.
There are divine truths and wicked truths. The wicked truth referred to here is that many adherents of Islam do not recognize the basic humanity of those that don't practice their worldview--and that includes many Muslims as well as non-Muslims.
Slavery still exists primarily in Muslim regions. There was a time--until the West stood up to it--that Europeans and the nascent Americans were enslaved or ransomed. One of our greatest stood up and said, "No more."