I was recently conversing with a young woman who is now Catholic but was raised fundamentalist Baptist. It sounds like her fundamentalist Baptist upbringing was even more strict than mine, so I don't want to lean too heavily on the fact that my experience has been different than hers. What I do want to talk about a little is this: She repeatedly said, as if this were definitely a bad thing, that the church groups of her youth were "white, middle-class, and Republican" and that they made one feel that this entire worldview, including economic ideas, was bound up with their Christianity. When pressed, she came down rather heavily on the alleged badness of uniting "right-wing" economic views with Christianity.
Had I been quicker on the uptake (I was too busy trying to think about how to give some pushback while remaining tactful) I would have pointed out that bishops of her own Church repeatedly tie up economics and immigration, neither of which are actually doctrinally essential, with Christianity. Indeed, it is considered to be something of the glory of Catholicism that it has economic views and economic encyclicals, some of which are a bit of an embarrassment to any free-market economists who also happen to be Catholic. What is sauce for the goose is sauce for the gander. Is it really a baaaad exclusionary tendency for "Bob Jones Baptists" to think of free-market economics, with a strong emphasis on human fallenness, human responsibility, and the dangers of centralized government as, in some sense or other, part of their Christian worldview but inclusive, loving, and not at all an overreach or "tying the gospel up with politics" for the Pope and bishops to think of anti-market economics and "immigration reform" as part of their Christian worldview?
But more: Any particular church or parish is going to be to no small extent a self-selected group, because there are always other places for people to go. It is perfectly normal human behavior to want to be able to talk about a variety of issues with one's friends at church, and it is perfectly normal human sociology for a tightly knit church to come to be to some degree homogenous across a variety of ideological issues. This is no doubt just as true of left-leaning local churches as of right-leaning local churches, especially when they are not "megachurches" and therefore actually have some sort of definite cohesion. Just how comfortable is a "white, middle-class Republican" going to feel in some of the evangelical churches presently catering to hipsters and seekers? How about at a Catholic church where the priest's sermons are often left-leaning in character?
It's important to remember too that to some degree the natural gravitation of like toward like is bound up with the idea that local churches should provide a sense of community. Perhaps one will get more diversity both of ideological and of sociological background if one's church is merely a place for the weekly meeting (e.g. the Mass) itself and is in no sense a larger community. If people scarcely know one another a church's de facto membership may be more diverse, but is that really what we want? Is it something we have a right to demand in the name of encouraging diversity?
Let me make it clear at this point that I actually do see both a tension in the church's goals, whether Protestant or Catholic, and also a distinctive way in which Catholicism is likely to be more diverse. As to the first of these, all churches are indeed trying to evangelize the lost. That evangelistic goal is going to have to mean a willingness to be friendly and welcoming towards those who come to one's church who don't fit in a purely social sense with those who are already there. It may well even mean explicit outreaches to all manner of people. Let me add here that one of the fundamentalist Baptist churches of my own upbringing has a regular outreach to the gospel mission and is by no means exclusionary of those "not like us" who show up at church. It is one of the most diverse churches I know, in economic, social, and racial terms.
As regards Catholicism, the emphasis on the Sacraments is in some ways orthogonal to the emphasis on community. Community is good, but if one is a real sacramentalist one goes to church in no small part to get the Sacraments, not to get together with other members of a club. I suspect that the "here comes everybody" character of Catholicism, of which many Catholics are rather proud, arises from the Sacraments. And that is not a bad thing.
Still, Catholics need community as well. I hear my traditionalist Catholic friends on the Internet talking about this all the time. Especially now, social conservatives are pretty lonely, and if your church (Catholic or Protestant) can be a community to encourage you rather than a place where you have to grit your teeth through left-wing platitudes in the sermon, so much the better.
So color me unimpressed with the complaint that the church of one's upbringing was too full of white, middle-class Republicans who were most comfortable with others like themselves. White, middle-class Republicans need Jesus too, and if they form church groups that look like themselves, they shouldn't be blamed any more than any other identifiable social group that forms church groups that look like themselves. Yes, as Christians we always have the tension created by the Great Commission, and we need to be aware of that. But if the upshot is still that a given church is mostly full of white, middle-class Republicans, it is not clear to me that this is per se cause for scorn or criticism. Yep, even if most of them believe in the free market.