WASHINGTON, D.C. (CNA/EWTN News).- Cardinal Daniel N. DiNardo of Galveston-Houston told over a thousand young people at a prayer vigil in D.C. that the pro-life movement depends on their loving witness in the face of a hostile culture.

"You are a good infection," the cardinal told the youth gathered at the opening Mass for the National Prayer Vigil for Life. "Do not underestimate your presence."

More than 10,000 people gathered on the evening of Jan. 22 for Mass at the Basilica of the National Shrine of the Immaculate Conception, including many young people from across the country.

The date marked the 39th anniversary of the Roe v. Wade Supreme Court decision that legalized abortion in America.

Cardinal DiNardo, who serves as chairman of the U.S. bishops' Committee on Pro-Life Activities, was the principal celebrant and homilist at the opening Mass, which was followed by confessions, a rosary, Night Prayer and holy hours throughout the night.

The Catholic University of America hosted almost 1,300 pilgrims overnight.

The vigil concluded on the morning of Jan. 23 with Morning Prayer and a closing Mass, at which Cardinal-designate Timothy Dolan of New York was the principal celebrant and homilist.

Participants were then able to attend the March for Life in downtown D.C., along Constitution Avenue to the Supreme Court building.

In his homily, Cardinal DiNardo spoke about the call of Jonah. Although he first ran away, Jonah eventually realized "that the call of the Lord is serious." When he finally responded to that call, his preaching converted the people of Ninevah.

"We are walking through Ninevah," the cardinal said, emphasizing the need for "personal conversion."

With millions of lives destroyed by abortion in the last 39 years, he noted the need for ministries of conversion, as well as compassion and mercy.

Through the work of such ministries, he said, "we witness the miracle of Christ's mercy and healing grace" as broken hearts are "made whole" and "filled with new peace and hope."

The cardinal also expressed grave concerns that the pro-life movement is threatened by recent attacks on religious freedom in America.

On Jan. 20, the Department of Health and Human Services finalized a rule that will require virtually all health insurance plans to include sterilization and contraception - including drugs that cause abortion - free of charge.

Cardinal DiNardo explained that this mandate violates the religious liberty and rights of conscience of Catholics and other religious employers by forcing citizens "to directly purchase what violates our beliefs."

He called for "timely and unwavering actions" to defend religious freedom.

At the same time, the cardinal expressed hope for the future, observing signs of good news, such as the "record numbers" of pro-life laws passed on the state level in recent years.

In many ways, the youth are "weaving Christ into our culture," he said, urging them to show the loving face of Christ to those who are hostile.

"Don't be compromised in your dedication to the protection of life."