Far from the truth, there may have been some Christian extremists who did some God awful shit (blowing up aboriton clinics etc).
HOWEVER, there have been literally hundreads of terrorist attacks by Muslims which have resulted in hudreads of thousands of deaths, and this is only in the last 30 years.
I would admit that only about 5% of the entire Muslim population are extremists/terrorists but when you're talking about a religion with 1.2 billion adherents, that is literally MILLIONS of terrorists.