Raised as a religious evangelical in the Deep South, Willie Parker had a straightforward view of abortion. He thought it was wrong. Then he went to medical school and became an obstetrician-gynecologist.

It still took years before he came to realize why some women might be offended by men legislating what happens with their reproductive organs.

“My life’s trajectory stoked a moral argument for the reproductive rights of women; that’s how I describe it,” Parker told me recently.

Parker, now 55, went on to become medical director for Planned Parenthood of Metropolitan Washington from 2008 to 2013. And he wrote a book, “Life’s Work: A Moral Argument for Choice,” which was published last year. In the nation’s ongoing fight over abortion — the Supreme Court heard arguments in yet another “pregnancy clinic” case just last week — Parker has emerged as a uniquely powerful advocate for women’s health care. The continued threat to abortion rights is why he’s speaking out yet again.

His trajectory is instructive. For it shows how attitudes can change — even when the subject is abortion and when both sides appear dug in especially deep.

Parker was born in Birmingham, Ala., and raised by a single mother. At age 15, he joined a Pentecostal church.

“As a young person, my Christian identity was far more important to me than interrogating the inconsistencies of my faith,” he wrote in the book. “So even as a middle-aged man, having spent more than a decade in training as an OB/GYN, and a subsequent decade caring for women, I retained that powerful Christian identity, constricted as it was by convention and custom. Abortion fell into the category of ‘should nots.’”

For Parker, the inconsistencies in his faith, as he called them, kept getting bigger and bigger. He said the moral hypocrisy was too obvious to ignore.

“In Mississippi, they have abysmal rates of poverty, infant mortality and maternal mortality, especially for black people, and they call themselves ‘pro-life,’ ” Parker said. “I will believe you are pro-life when you start showing as much concern for people outside of the womb as the ‘people’ inside the womb.”

Parker said it was science that aided his changing views on abortion.

“Life is a process, not an event,” Parker explained. “Think of how a clock comes together. You have the arms, face, the gears. But you don’t call it a clock until it’s all working together. That’s how human life develops.

“Life is still developing after the birth and we need parts to make it a fully functioning human being — education, nutritious foods, housing, employment,” he added. “But the right-to-lifers aren’t interested in providing those resources. It’s easy to love the fetus because you don’t have to feed it, house it, provide economic opportunity for it.”

Parker noted that after becoming a born-again Christian, he took a vow of celibacy, and honored it until he was a grown man and almost out of college. He does not regret the decision.

“My delay was related to my religious values and served me well,” Parker said. “It kept me on a disciplined pathway.” He learned early on that women don’t get pregnant by themselves.

“We have to stop sending mixed messages to boys and girls about sex,” he said. “We need to try just as hard to keep boys from becoming teen fathers as we do to stop girls from becoming pregnant. As Frederick Douglass said, ‘It’s easier to raise a healthy boy than fix a broken man.’ ”

In making his dramatic transformation, Parker did not shed his conservative home training like some ill-fitting snake skin. He still embraces traditional family values.

“I claimed a new faith identity and began practicing compassion,” he said.

That, he said, is pro-life.

To read previous columns, go to washingtonpost.com/milloy.