I think creationism remains pervasive in the conservative evangelical church in America for reasons that have far more to do with sociology than with the natural sciences, theology or even biblical hermeneutics. Creationism is a boundary marker for conservative evangelicals. As such it is analogous in that community to a whole range of other diverse boundary markers they have: biblical inerrancy, soteriological exclusivism, patriarchy, and of course conservative opinions on sexual ethics, homosexuality, gender, abortion, race, political party affiliation, climate change, and so on.
These boundary markers originate for various case-by-case reasons, some good and some bad; but once they reach a certain threshold of acceptance, cultural conformity takes over and becomes the dominant factor in their maintenance over generations. Dissecting and arguing with the underlying reasons that inspired these markers to rise in the first place - the hermeneutical, exegetical, theological, scientific, historical, philosophical, legal and/or moral reasoning that originally lent them credence - is almost beside-the-point. And violating any one of them by holding, let alone being vocal about, different opinions can lead to outcomes ranging from occasional awkward conversations to outright severing of relationship. (And lest you think I’m picking on conservative evangelicalism too much, I think most or all cultural groups behave this way.)
That said, the boundary-stones are not immovable and do rise and fall over time - even rapidly. We’re seeing that happen now with homosexuality. In broader American culture, increasing acceptance of homosexuality is now affecting, and will continue to inevitably affect, the perception of homosexuality within conservative evanglicalism as well. In a rapidly short period of only a couple of decades, the broader culture has moved on homosexuality from “don’t-ask-don’t-tell” acknowledgement and co-existence, to acceptance and tolerance, and now closing in on welcome, encouragement and affirmation. And the same thing will happen within the conservative church in the next couple of decades, until traditional negative views of homosexuality are seen as simple bigotry - just as has already happened in the conservative church following the broader culture with respect to race (miscegenation, etc). And so the “homosexuality boundary marker” will fall. Biblical arguments, scientific arguments, moral arguments and philosophical arguments about whether it should or not will matter little, once the new paradigm has entrenched itself and cultural momentum takes over.
The only thing that will make evolution acceptable within conservative evangelicalism, then, is for the same sort of thing to happen with creationism (though perhaps less dramatically, as unlike sexual orientation, evolution poses no “threat” in everday ordinary life). Factors ranging from “beachhead” pro-evolutionary pastors, churches, and para-church organizations (eg Biologos), to increasing millenial-generation acceptance of mainstream science, will chip-away at creationism until - once evolution-acceptance reaches that threshold point - social momentum will carry it the rest of the way.
Incidentally, there will of course be factionalization in all of this. As a new paradigm becomes established that is unacceptable to more-traditionalist holdouts, they will separate. Evangelicalism will fracture - it is already starting with progressive evangelicalism (aka “post” evangelicalism) having less in-common theologically with its conservative roots than it does with mainline Protestantism. It remains to be seen whether evolution/creationism is one of those wedge issues (to borrow the expression from Philip Johnson in not-at-all the way he intended it) that lead to division.
Anyway, that’s how I see it, and it’s one reason I find myself having little interest anymore in arguing the good reasons for accepting evolution with anyone.
