I don't think was or was intended to be a Christian event. It was a free speech event and free speech is the right of all Americans regardless of religious beliefs or other belief systems.
I totally agree it was well within the right of free speech and the first amendment. No argument there and no tears for the terrorists that were dispatched tonight. In fact I have a lot of anger towards those who perpetrate such acts.
However, just because you can do something, and have every right to, doesn’t mean you should. We don’t have to lower ourselves to the level of the lowest common denominator. Not a popular view, I know, but my feeling none the less.