So, its ok to guess and take into consideration everything except his muslim ranting on his facebook page and the beheading (something that at this particular time is well known to be an islamic method of terror) - got it, glad you're so open minded on this one. Poor misunderstood guy, he must have just had a bad day and snapped. End of story and thread I suppose.
Beheadings are also widespread in Mexico right now, nothing to do with any religion. It is a very effective way to kill a person and create fear amongst others.