I think you're overestimating the influence of evangelical Christianity on U.S. politics. Evangelical positions have more to do with making a cultural statement than seeking to implement Christian law. You'll be surprised with how many people supported Mike Pence, while he was Governor, only because they didn't want a Democrat in his place. The same can be said about those who take a evangelical position despite not being religious. A not insignificant amount of people would tolerate a pro-life position in the interest of opposing a politician they detest.

What we view as evangelicalism is actually irreligious individuals making a cultural statement. Evangelicalism is a symptom of America's culture war. Not the other way around. A culture war that progressives, in this country, are attempting to import on a daily basis.