"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached"

Choosing that statement to quote, rather than other writers, depicts unmistakable animosity to Islam. It was an insult to do so.

I would guess that the reason the Muslim world reacts so violently to the Pople repeating it is that over the centuries that statement
has rankled.

Come on. If one of their spiritual leaaders gave a public lecture in which he said that Christianity holds "only things evil and inhuman", christian leaders from Falwell and Robertson to the Pope himself would decry such a view of the religion they hold dear. They wouldn't take to the streets and burn down mosques - it's not our style- but one of them might well call for the assassination of the said leader.