I don't think it's a great strategy to try and seek a religious motivation in every attack that happens because it suits a particular narrative. If a guy who happens to have been Christened but otherwise has nothing to do with the Church shoots up a school then we don't scramble to call it a Christian assault on learning. The people that lived with this guy claim he wasn't religious, he hasn't left a video, there's none of the usual extreme cleric teachings that usually surface pretty quickly after the fact, and it took him until halfway through the event to phone the police and say there was an ISIS connection.
Sky were desperate to paint it as a Muslim extremist hating our way of life story, and while I don't doubt that is a problem, it doesn't look like this was an example of it.