The "mainline" Protestant churches weakened sharply in both membership and influence while the most conservative denominations (such as the Southern Baptists) grew rapidly in numbers, spread across the United States, had grave internal theological battles and schisms, and became politically powerful.
While the former trend did not come at the expense of the latter (it represented different fertility and retention rates, not switching), to the media and many ordinary observers those developments signaled the aggressive swelling of religious strength.
After World War II, some conservative Christian denominations including the Southern Baptists, Missouri Synod Lutherans (LCMS), the Church of God, Pentecostals, Holiness groups, and Nazarenes grew rapidly in numbers and also spread nationwide.
LCMS would see a split in the 1970s which would ultimately lead to the forming of the Evangelical Lutheran Church in America, while the SBC would face its own battles resulting in the Southern Baptist Convention conservative resurgence.
[5] Byrnes and Segers note regarding the abortion issue, "While more theologically conservative Protestant denominations, such as the Missouri-Synod Lutherans and the Southern Baptist Convention, expressed disapproval of Roe, they became politically active only in the mid and late 1970s.
However, the political involvement of churches ranged from actively participating in organizations such as the Moral Majority and the Christian Coalition to adopting the much more indirect and unorganized approach of Missouri Synod Lutherans.