In the area of women’s rights, for example, the driving force was mainline protestants who wanted prohibition, in opposition to recent immigrants: https://www.wpbstv.org/prohibition-and-the-suffrage-movement.... If America had remained an Anglo-Protestant society, it likely would have developed on a similar trajectory as Canada, the UK, and Australia on issues like abortion. Remember, Roe v. Wade had five Nixon and Eisenhower Republicans in the majority. The party shifted positions on the issue with Reagan because it was a way to flip a large number of catholics, who had overwhelmingly voted democrat until then. Evangelical protestants plus religious Catholics was a big enough coalition to offset mainline protestants on the issue.