Converts to any religion are usually more ardent,passionate and "extreme" than people born and raised in the religion. Only, you rarely hear of "extreme" Christians or Jews trying to blow themselves up and everyone else with them.
The most dangerous aspect of islam is the principle that "the end justifies the means when it comes to spreading the religion." That eliminates any elevation of behavior or sense of decency or rules of dignity from warfare from islam. That alone give islam its depravity in proselyzing and war.
IMO, it is that one concept that proves the demonic design of islam.