Evangelicals have no long-standing theological problem with abortion. My parents have been married for longer than evangelicals have been against abortion. Evangelicals in the 1970s didn’t care about abortion. Being against abortion was a Catholic thing. Evangelicals thought abortion is unfortunate, but not evil.
Bob Jones University, an evangelical school, had a segregationist dating policy. It means what you think it does - they wouldn’t allow white students to date black students. They also wouldn’t admit black students who supported interracial marriage. This was in the mid-70s. Loving v Virginia was nearly a decade in the rearview mirror. The government threatened to revoke their tax-exempt status as a university unless this Jim Crow shit stopped. The school sued, and this eventually went to the Supreme Court. The Court, unsurprisingly, agreed with the government.
What was clear to evangelical leaders, then, in 1983, was that out-and-out racism was no longer going to be tolerated. What could they focus on that would have the same effect? What could rally the base without openly espousing racist views?
Reagan, with his “welfare queens” dog-whistle politicking gave them a like-minded politician glad of their support. And Surgeon General C. Everett Koop was only to happy to tell people what he thought of abortion.
So here we are, thirty-five years later, with every evangelical doing their damnedest to pretend that evangelicals have always been against abortion. They’ve lied themselves into believing it, and now they claim they’re against birth control too. That’s even more spurious - If they actually thought life begins at conception, then birth control would be a necessity, because fertilized eggs being rejected is the norm. Most of what they want to call human life never even gets implanted in the womb, or lasts very long if it does. And if they cared about life, welfare programs ought to be the most important, to ensure everyone has a good standard of living worthy of human beings.
But they don’t care about those things, so the only conclusion is that they are not pro-life. They just don’t want to see family planning and health care go to women, people of color, LGBTQ folks, etc.
It was never about being pro-life.
(and incidentally - Bob Jones v US was an 8-1 decision. Who was the dissenting voice? None other than William Rehnquist. Who was elevated to Chief Justice by Reagan when Warren Burger retired a few years later. None of what has happened has happened by accident)