Because people have a tendency to blame or condemn an entire group over the acts of one person. Note that focal point of the OP is that the murderer was (or claimed to be) a Christian. That seemed to be the main thrust of the thing.
That's based on what the murderer himself posted, though. The OP didn't come up with those social media posts himself, so how is it condemning an entire group to point out what the murderer had already posted? Besides, I would say that if you feel it condemns you or your entire group then maybe that's a good reason to think about why you apparently feel like you're being placed in the same bucket as this guy. I have no problem as an Orthodox Christian saying that the murderer certainly was a Christian of some kind (it's a rather low bar to take someone's own self-identification as a Christian as an indication of what they claim to be following), while at the same time maintaining that I see nothing of the love and guidance of our Savior in what he did. That should be the least controversial statement ever, I'd hope.
Is it that you feel like you can't say something similar without betraying a fellow Christian in favor of 'the world', or that you're just tired of having your religion associated with wackos, or....? If it's the latter, I 100% agree, but unfortunately that's the reality of belonging to a communal religion like Christianity, whereby unfortunately given the way that it has developed in the West in the last 500-odd years since the founding of Protestantism, there's not a lot of quality control or even holistic pastoral guidance. Time was, in the long long ago (and now, for the more traditional churches), people like the shooter who would send out messages threatening violence or even commit violence could be dealt with by nearest ecclesiastical authorities (see, e.g., the condemnation of the earlier-mentioned Bashmurians by the Coptic Orthodox Church of the time; it is only in later Coptic sources that they were reevaluated positively as Coptic proto-nationalists and resistance fighters against Islamic oppression). The result was often mixed at best (the Bashmurian revolts still carried on for a few centuries), but least there was clear guidance, so that no one could say that the Church was somehow behind the revolts or in cahoots with those participating in them. (Not that this stops anyone from doing that, then or now.)
The difference between this setup and some lone wing-nut carrying out what is essentially stochastic terrorism (wherein his inspiration can't be traced back to a single leader or group of them who told him to do this, a la Al Qaeda or ISIS or whatever) ought to be obvious enough, but so long as the dominant form of American Christianity continues to be one that prizes the individual's interpretation of whatever they're taking in (in keeping with America's secular individualist ethos), we're
all going to have to deal with the reality wherein the maniac with his own idea of what taking the 'narrow road' means -- and the armaments to clear his way to insta-salvation for being so darn righteous in standing up against a world full of rainbow sinners -- does more to represent our religion in the imagination of the emerging possible non-Christian majority than one or a million sermons about forgiveness or exercising mastery over the passions or anything more traditional than "gay bad" ever could. 'We' (in quotes because it even includes those of us who are in traditional churches that don't put up with this entire approach to religion) have entirely lost control of the messaging or branding of Christianity, to use marketing terms that are American Evangelicalism-compliant. Now I want you to think about this for a second: in this context, is it more important that you register that it is unfair that some of our detractors are painting with too broad a brush when they present such events like they're embraced by the majority of Christians (most of whom don't even live in the USA, of course), or is it more important that we not give into feelings of being unfairly maligned and instead join the majority (Christian and non) who see an event like this happen and say "This sort of thing should never happen, and the fact that it is being given religious or quasi-religious justification is indicative of a major sickness in the soul of American Christianity that needs to be addressed holistically and pastorally (read: to the people in the pews, in a way that they will be receptive to precisely because they rely on an assumed embrace of Christianity by those same people) if we ever want this to stop"?
A loaded question, no doubt, but it was only a few days that I pointed out to a poster on this website that the virtual salivating that they were doing at the thought of denying gay people rights that they now legally have was really weird and off-putting, so I don't think we're as far away from the basic impulses that can drive this sort of thing to happen as most of us would probably like to think we are. Again, going back to traditional Christian anthropology for a second, I am against the LGBT-ification of existence in large part because of the
dehumanization it does to people and the whole idea of what it means to be human, but I also recognize there is a world of difference between that type of dehumanization, which is completed once the mind is captured by the secular ethos to the point that breaking out of it to return to any earlier/more well-established way of looking at the world feels like 'going backwards' (which is an idea that itself really only makes sense if you believe in the infinite perfectibility of man without God, which is another cornerstone of the secular worldview), and the type of dehumanization accomplished with literal bullets that leave people dead in the street because they hung up a flag that someone didn't like. At least the former can be argued against and people can be challenged regarding their assumptions about the world. There's no arguing with bullets. Bullets are stupid.
It would be good if people would think about these dimensions of the war we are fighting for the soul of our religion, and for its image and reality before wider society, rather than giving surface-level takes of "gay is bad" or what have you. How does "gay is bad" answer the deep longing for wholeness and genuine participation in He Who is without beginning or end? Not to put too fine a point on it, but how does "gay is bad" answer that longing in people who swim everyday in the puddle-deep wastewater of American secularism and hence have already completely bought off on its anthropology without even realizing that this is what they are doing, and therefore are already totally on board with everything LGBT and other person-mutilating doctrine? To say that repeating the message of "gay is bad" is not winning them over is probably the understatement of the new millennium, but my point is more that it doesn't prompt any deeper self-reflection, either, so I don't see how simply identifying that is good enough to really help anyone in any fashion. It goes beyond whether or not it 'needs' to be said, to me (because again, I'm coming at this from an Orthodox Christian perspective, wherein this is a settled issue, so it is very rarely discussed, at least internally in the Egyptian Church), and instead enters the realm of "What else could we be saying if we want to get to the roots of what we have to offer as Christians that is sorely lacking in society as it has evolved since the widespread abandonment of Christianity following the so-called 'Enlightenment' in Europe?" Because
that's the true background of American Christianity, as we know it today: Enlightenment values, perhaps mixed with some pietistic flourishes from the later echoes of the Protestant Reformation. In other words, compared to more traditional Christianities like Orthodoxy or traditional Roman Catholicism, the roots of Christianity in modern America are already largely secular. The only thing that has changed more recently that I can tell is that people no longer feel the social pressure to self-identify with something that they largely never practice in any sense anyway unless they happen to win an Oscar or a football game.
Secularists being mean to or realistic with Christians didn't create the mess that is American Christianity, and no one can fix it by just being straight
even harder than ever before or whatever. This requires real work, real soul searching, and I'm going to say real
metanias on the part of those who see American Christianity (read: Evangelical Protestant hegemony; would that American Christianity stood for anything else in our time) as worth saving. And, fittingly, no one else can do it for you. It has to come internally from the people themselves.
Sounds like maybe you're talking about sugar coating it to make it more palatable.
With respect, it sounds like it to you because we are just too far apart in mindset. Rather than sugar coating anything, what is actually going on is that I'm not going to clap like a trained seal with delight at your recognition that sin is sin, in the same way that (e.g.) Muslims and Jews get no special commendations from Orthodox Christians for being able to count when declaring, as their respective religions do, that God is one. That's the basics, which do not destroy any further distinctions that are to be made (i.e., why Judaism, Islam, and all other non-Christian religions are false and not salvific).
You don't even need to be a Christian to know that Christianity is against homosexuality, so my question is what are you doing with the truth that you already recognize? Are you using it like a cudgel to beat people with it until they magically stop 'being gay' or supporting gay or whatever? I have no interest in that, frankly. My own sins are what will condemn me before the Just Judge, not others', and even then I would rather show mercy to an errant person than be harsh, and by that lack of mercy make obvious the spirit that is truly driving me, and that that spirit is not that of the One about Whom we pray in the closing lines of every hour of the Agpeya that He "does not desire the death of the sinner, but that he returns and lives." We want to return to God with as many saints around us as we can, which probably means that at least some of them will not be ones we necessarily recognized while we and they struggled upon the earth together. Read up on the story from the life of Abba Bishoy regarding the miracle of his carrying Christ upon his back in the desert, if you are interested in what this means in practice for Orthodox Christians. That's not just an interesting story -- it teaches us a thing or two about not being in such a hurry to be 'right' (as 'we' already are, not because of any great luck or superiority ourselves, but because
the faith itself was delivered once for all, perfect and complete from the holy mouth of our Savior and His most blessed and honored apostles and disciples) that we leave others by the wayside.
Personally I go by how Jesus, Paul, Moses, and the Prophets are on record when it comes to speaking against sin which is extremely harsh in numerous instances. Many seem to want to have those numerous instances removed to where there's just some sort of warm fuzzy feel good about yourself Tony Robbins-ish remnant.
To greatly abbreviate the prayer of the absolution of the ministers from the Liturgy of St. Basil, I go from the mouth of the all-holy Trinity, and from the mouth of all of our holy fathers past and present, and from the mouth of the 318 assembled at Nicaea, the 150 assembled at Constantinople, and the 200 assembled at Ephesus.
(Not found: Tony Robbins or any other modern guru. Can we please stick to explicitly Christian examples, since we're two Christians having this conversation?)