I was raised a Catholic and we certainly didn't ignore the old testemant in our lessons on Christianity. I'm not really sure why you are talking about going off the teachings of Jesus instead of the bible as if people throughout history could just go up and ask the bloke. People got their teachings from the churches, as priests could read in Latin.
He may have previously been a practicing Muslim but he doesn't speak for all of them. From your description it sounds as though he has left a radical branch of Islam which is a good thing. You must understand that I'm not arguing in favour of radical Islam but that we, as a collective, properly differentiate between Muslims who live in peace and those who don't so as to not label them together and alienate those who are living good and honest lives.
And Gordo that was clearly not the point of my argument. You're ability to take everything out of the context of their meaning is astounding. I'm trying to show that Islam shares a brutal past with many other religions and was simply using Christianity as an example since it is the largest in the world.