This is horrible. Of course we will have to wait till the now-mandatory, ‘too late for outrage’ period has passed before we see somewhere on page 23 for half a column inch that he was a devout Muslim and this was an honor killing as his wife forced him out. But for the moment we know his family seemed great, was a good American family who liked all aspects of US life and supported the troops but were Iranian Muslims. Right up to the point where the estranged husband slaughtered everyone dressed as Santa, they were an excellent example of the moderate Muslim.
And frankly even if this was not an honor killing, an Islamic background and imprinted value-set would have been at least a factor in his decision to do what he did.
Here is an article from the Star-Telegram’ which says they were a Muslim family but celebrated Christmas as an American cultural practice.