The average American, including Muslims, is woefully ignorant of the beginnings of Islam. It started with the sword and continues to this day. Muhammad gave people the choice of either converting to his religion, living as virtual slaves under Muslims, or dying.
Muhammad personally led attacks on innocent caravans to finance his religious wars. He rewarded his men with women for raping and use as sex slaves, stolen booty and the bloody killing of his enemies.
One example tells it all. In A.D. 627, the last Jewish tribe in Mecca, the Banu Qurayzah, surrendered, but refused to convert to Islam. Muhammad ordered perhaps 800 men to be decapitated in front of their women and children. Torches were lit so the slaughter could be accomplished in one day. Then the women were raped and the children brought up as Muslims.
The Islamic State, also known as ISIL or ISIS, in 2015 offers a true representation of what an Islamic society looks like. They advertise normal historical Islam, not radical Islam.
William Landers Gutel, Lansing, Michigan