I think that you misunderstand Christianity. Christians are followers of Jesus and yes of course follow the Bible and believe that what it says is correct, wise and good, that is their faith! Christians know that praying to God can change outcomes, behaviors, situations, attitudes etc.; so yes, offering thoughts and prayers is a way to help people cope/deal with a difficult situation and a loving thing to do.
This is no different from other people of differing religions/beliefs following their ‘sacred texts’.
I am sure that you could find more examples to share just as I could also provide examples of the bigotry and demonization of Christians for their beliefs, and some that have paid a hefty price for seemingly minor infractions that 50 years ago nobody would bat an eye at.
We do live in a country where people are free to worship whoever/whatever they choose. You will find good and bad people in all those groups because we are still all human beings and therefore subject to our human sinful natures; some more than others, some not able to control their impulses etc. This should not be used to paint all people of one religion in a bad light, whether Christian, Jew, Islam, or Buddhist etc. I think that most people realize this but there are those who will demonize an entire faith based on the sensationalized things they see/hear/read etc. especially in this politically polarized/charged time in our country. The man you talk about (the New Zealand shooter) stated that he purposefully did that because he wanted to cause racial/political divides within our country. That is just incredible to me that someone from a different country would want to do this, that should scare us all and make us all think. I also think that our politicians, including the President, should speak out more on hate crimes like this.
This country was founded on religious freedom, meaning you are free to choose/worship whoever you want. It was not meant to not have Bibles, 10 Commandments plaques etc. excluded from schools, Gov. buildings etc., hence that is the way it was done in the past and why some are there. Our society has been moving away from that for years. People will, and are allowed, to have differing opinions about that. We should all be able to come together and find a solution meeting in the middle somewhere. But unfortunetly our politicians and news media seem to do just the opposite, either intentionally or unintentionally dividing people with their sensationalism and bias reporting of such stories. IMO, it is not helpful to our society as a whole.
I am still not sure what privilege you think Christians have or why you think that Christians think you are “expendable”. I have been a Christian my entire life so I know and have been around many other Christians and I assure you I have never met any who feel that non-Christians are expendable. Most I know believe as I do that you are free to make your own choice whether to be a Christian or not, Jesus is a true gentleman and will not force himself on anyone. “I stand at the door and knock…” (Rev 3:20).
And in this country all are privileged because all can worship whoever/whatever they want , or not believe/worship anything. Not all countries can say that.