Oh Noes! Let's run around like chickens with our heads cut off! Let's decry about the decline of American civilization! Gloom! Despair! Agony on me!
Let's just analyze that statement for a bit.
First, White Christians are still the majority in 31 states, and if you look closely at least 5 of the 19 listed are within 4%. So we could say that White Christians are the majority or almost the majority in 35 states and a significant and over 1/3rd of the population in 13 more.
Second, the key word "white." I suspect that some people in reporting this are going to drop that word to make a bigger deal of this than it is. But guess what? First church 100% not white. Vast majority of 1st century Christianity, not white. IF you want to get particular about how white, say northern European white, its a couple of centuries before even a significant percentage of Christians are "white." According to a Pew Research Center report about 62% of Christians live in areas that would considered "non-white." This does not take into account the number of Latino, Black, and other minorities in North America and Europe.
Now, let's get real about this.
Our racial distinctions in general are arbitrary and ultimately meaningless. We could, perhaps, talk meaningfully about cultural and ethnic distinctives, but in the end they have nothing to do with race. Especially in America. Yes, races often still self segregate. Yes there is racism in America. I am not saying that skin color does not effect how one lives in the USA. I am saying that the key word in White Christian, Black Christian, Yellow Christian, or Blue Christian is "Christian" and that those groups have more in common when it comes to basic values and morals than they have differences. So the fact that "white" Christianity is a minority in 19 states tells us nothing about the real religious landscape.
Then there is the idea that people self identifying as non-Christian is a bad thing. It is not. It is, in fact, simply more honest. How long have Christian leaders bemoaned the numbers on their rolls that never attend? How long have they doubted those that say they are "Christians" but never participate in any kind of Christian community? All that has really changed is that the cultural imperative to fit in no longer includes identifying with a Christian group.
What if it has? What if we see a growing trend in the decline of Christianity in the US?
There are no "what ifs" about it. We will. We will also see more diversity in Christianity. We will likely, hopefully actually, see more more diversity in individual congregations as like minded Christians begin to realize that racial differences are less important.
Also, an end to cultural religion can only be a good thing. No matter what that religion might be. When faith is tied up with national identity both are adulterated and warped. I can be a patriot and not be Christian. I can be Christian and not support a particular political agenda. I can be a good person and a good member of my community and be neither Christian nor affiliated with a certain political faction.
The sooner we learn that faith has nothing to do with the color of our skin or our nationality the better.