(RNS) — Judge Amy Coney Barrett holds that she can compartmentalize her religious convictions and make judgments on constitutional grounds only.

“My present church affiliation or my religious beliefs would not bear in the discharge of my duties as a judge,” she told the Senate Judiciary Committee at her confirmation hearing in 2017 when she joined the 7th Circuit Court, a theme she continued in the answers she gave the committee in the past days.

But legal rulings on topics such as abortion, stem cell research, in vitro fertilization and birth control are colored by how we understand and define not just the morality but the practical reality of these issues. And as Barrett takes her seat on the Supreme Court, it’s worth considering that her understanding of abortion, birth control and reproduction differs even from most pro-life Americans.

Pro-life churches in America, including mainline Protestant and evangelical congregations, have pragmatic answers to moral questions surrounding abortion and sex. For them, contraception is acceptable, especially within marriage.

Similarly, although they view abortion as wrong, use of fetal tissue in medicine is a different matter. If science can use stem cells from fetal tissue to develop treatments for diseases such as Parkinson’s and Alzheimer’s, it feels like a silver lining to a dark cloud.

One last example: If a couple can’t conceive naturally, these churches support couples seeking help from fertility clinics, which offer in vitro fertilization, accomplished by implanting an embryo.

When many Protestant pro-lifers say they oppose abortion, they mean the removal of the fetus by scraping (D&C and D&E), saline injection or suction. The “morning after pill” is seen as an excellent contraceptive alternative to these forms of abortion.

Supreme Court nominee Amy Coney Barrett listens during a confirmation hearing before the Senate Judiciary Committee on Oct. 14, 2020, on Capitol Hill in Washington. (AP Photo/Susan Walsh, Pool)

These American Protestants’ views rest on the legal concept of proportionalism, which claims we should do the best thing for the most people without diminishing the rights of any individual. Based on Enlightenment philosophies of liberalism and utilitarianism, proportionalism seems like second nature to most Americans. Look around, see what your choices are, and pick the best option available.

The governing body of the Roman Catholic Church, the Magisterium, rejects proportionalism, along with the morning after pill, in vitro fertilization and all the other above examples. It builds on philosophies that precede the Enlightenment by more than 1,000 years; liberalism and utilitarianism were not even invented when Catholic moral theory was first being written.

The early church fathers, and theologians throughout the Middle Ages, sought concrete, consistent rules that were easily applied. In a world where few people could read, and there was no mass communication, the Magisterium needed a concise way to teach about sex and birth. Priests were trained that sex and reproduction are intrinsically linked and that sex should lead to the possibility of procreation.

Even though new technologies have brought us to new moral dilemmas, this ancient teaching remains. The most recent papal teaching on the subject, Paul VI’s 1968 encyclical Humanae Vitae, reaffirms it, stating that “Marriage and conjugal love are by their nature ordained toward the procreation and education of children.”

In this view, all sex must be open to reproduction, and all reproduction must come as a product of sex. The church’s teaching rejects all forms of sex that do not relate to children — including use of condoms, the morning after pill and homosexuality. In this view, life begins at conception, and anything that disrupts or prevents that conception is a mortal sin. And because in vitro fertilization does not entail sexual intercourse, for strict Catholics, it, too, is immoral.

Many American Catholics have moved away from the most conservative teachings of the Magisterium and have chosen to ignore teachings about such things as birth control and homosexuality. This is a difference between Joe Biden and Amy Coney Barrett. Biden’s Catholicism reflects American ethics. Barrett’s Catholicism follows the Magisterium’s teachings to the letter.

This brings us to the question of embryonic stem cells in American medicine. Protestants, evangelicals and even some Catholics, such as Biden, widely accept using embryonic stem cell lines produced by the tissue of an aborted fetus to advance science and health knowledge. Most Americans believe life begins at implantation, which happens a few days after fertilization, when the fetus attaches itself to the uterine wall.

The Vatican teaches that, because life begins at conception, embryos, whether frozen or aborted, are human beings who cannot be used for research of any kind. Thus, Regeneron, part of the cocktail given to President Trump for his recent COVID-19 infection, would be outlawed by Catholic social teaching because it was created using aborted fetal stem cell lines.

Indeed, without access to pliable and flexible fetal stem cells and their lines, most medical research would come to a halt.

Barrett may well live up to her vow to compartmentalize her faith. If she succeeds, she’ll no doubt owe it in part to the unprecedented scrutiny her votes and opinions on faith-related issues will receive from a nation that disagrees with her stance. 

(Kathy Rudy is a professor of gender, sexuality and feminist studies at Duke University and the author of “Beyond Pro-Life and Pro-Choice: Moral Diversity in the Abortion Debate.” The views expressed in this commentary do not necessarily represent those of Religion News Service.)