Unfortunately, that simply ignores the fact that wherever Christianity has not opposed islam by the sword, Christianity as a social/cultural force has died.
Would to God they all converted, but conducting oneself according to hopes that have an unblemished record of failure is simply insanity.
While ancient Rome may have been a ravening beast, it did have some measure of honor and nobility. By analogy, islam is little more than a disease; the more circumspect it’s adherents, the less human (in the philosophical sense) those adherents becomes.