Watch the video segment on the article till the end "no signs of forced entry or defensive wounds." found a large Israeli flag that appeared to be untouched. This was, as others have said, someone they trusted and that they knew. And in my opinion, it's weird that some people seemingly want it to be otherwise.
If it's not a targeted religious attack doesn't that at least put some kind of silver lining to an otherwise heartbreaking and unthinkable loss?