WASHINGTON, D.C. — Among the tens of thousands of pro-life demonstrators in Washington, D.C. on Jan. 24 for the March for Life was a group of high school students from the Bronx. They had several banners, the longest of which stretched clear across Constitution Ave. as they marched down it.

It took almost the whole group to hold it. In large red letters on white fabric was written, “PEACE NOT WAR. PRO LIFE. PRO IMMIGRANT. RENT CONTROL. HEALTH CARE. GUN CONTROL.”

The display stood out in a crowd that had plenty of prominent visual signs of support for President Trump, whose administration has not aligned with most of what the students’ banner professed. Trump was cheered while he spoke at the rally on the National Mall before the march, the first sitting president to do so.

The Bronx students’ political leanings may not have aligned with those of many groups they marched with, but the philosophy their banner promoted positions them as adamantly opposed to abortion as it does to anti-immigrant sentiment and loose gun regulation.

That philosophy is known as the consistent ethic of life, or the “seamless garment” theory, as it was first called by Eileen Egan, a longtime Catholic peace activist and social justice advocate. Egan lived from 1912 to 2000, and participated in many of the momentous events of the 20th century.

She was a longtime friend of Mother Teresa and she marched with Dr. Martin Luther King in Selma, Alabama. During World War II she worked with war refugees and Holocaust survivors. She was influential in convincing the United Nations to recognize conscientious objection as a universal human right. She protested for farm workers in the U.S. with Dorothy Day.

Egan coined the term seamless garment to challenge fellow members of the pro-life movement who supported the death penalty. It is a reference to the biblical verse John 19:23, which describes the tunic that Jesus wore to his crucifixion as seamless from its top to its bottom. The idea, Egan said, is that a life-affirming principle must be applied consistently across all issues.

Critics of the theory have charged that it blurs the lines between those who oppose abortion — what they consider the gravest immorality — and social issues that are more political in nature. Some have also said it provides cover for politicians who support legal abortion but are able to claim the pro-life label.

In 2013, Archbishop Gerhard Müller, prefect for the Congregation for the Doctrine of the Faith, criticized it in a speech at the annual Pontifical Academy for Life. He concluded his critique with a statement about the theory’s implications for the Catholic Church’s teachings on contraception and sexuality:

Our teaching is based in an inspired vision of the meaning of love wherein the sexual act finds its proper place as an expression of nuptial intimacy and openness to the livegiving creativity of God. In marriage, sex is an expression of love with a particular and intrinsic meaning. Once the sexual act is removed from this defining context - the “seamless garment” begins to unravel.

The theory was popularized by Cardinal Joseph Bernardin of Chicago. He was a vocal opponent of the use of nuclear weapons and abortion and used the seamless garment theory to fold other fundamental aspects of life into an expanded platform. He wanted to unify conservative and liberal Catholics who were split on many of those issues.

He criticized the use of the theory by anyone who did not oppose abortion, as critics charged.

In a speech in Portland, Ore., Bernardin said, “When human life is considered cheap or easily expendable in one area, eventually nothing is held as sacred and all lives are in jeopardy.”

Micah Danney is a Poynter-Koch fellow and a reporter and associate editor for Religion Unplugged.