I doubt if the guy was influenced by any newspaper, or anyone single individual or group trying to subvert him for any political or ideological doctrine.
More likely I think he was someone who was influenced by the constant threat and numbers of incidents inflected by individuals and groups who do want to see a worldwide domination of their culture and values. Many it seems willing to use violence against any who oppose. Almost every day now there are reports on the news of some incident or other related to Muslim terrorists. It was only a matter of time to be honest.
As for the racist comments, yes there probably are a few on this board as there are elsewhere but this is NOT a race issue.
I hear arguments about our involvements in the middle East, yes it certainly inflamed the situation. But what about the rest of the world?. How do you explain the incidents sweeping across numerous African countries, and the Far East
ISIS at the moment, but what about the Taliban, Al-Qaeda, Al-Shabaab, Boko Haram, Darul Islam.