Mary Ann Lundy was born in Morgantown, West Virginia on December 23, 1932. She received a Bachelor of Arts in English and Spanish from West Virginia University in 1954 and graduated from Union Theological Seminary in 1957 with a Masters in Divinity. She began her career teaching English, Spanish, and choral music in California and in Idaho. From 1972 to 1980 she served as the Assistant for Ministry at McKinley Presbyterian Church in Champaign, Illinois.

Lundy moved to New York in 1982 when she became the director of the National Student Young Women's Christian Association. In New York, she established a regional coalition on sanctuary and became co-chair of the Sanctuary Committee at Riverside Church. In 1986, she helped transport a refugee family from Tucson, Arizona to Riverside Church. That same year Presbyterian minister John Fife, along with sixteen other leaders in the Sanctuary Movement, were tried by the U.S. government in Tuscon, Arizona for providing aid to refugees. Mary Ann Lundy and eleven of her fellow sanctuary activists were called to testify in the trial. Lundy and two other activists refused to testify and were held under house arrest for the duration of Fife’s trial.

Lundy became the director of the Presbyterian Church (U.S.A.) Women’s Ministry Unit in 1987 (the unit was renamed Women's Ministries in 1994). She also served as co-chair of the U.S. committee for the World Council of Churches’ Ecumenical Decade: Churches in Solidarity with Women that lasted from 1988 to 1998. Part of this work called for an ecumenical conference on feminist theology. Alongside Sally Hill of the Minnesota Association of Mediators, and Judith Strausz Clement of Seattle, Lundy organized Re-Imagining, a 1993 gathering in Minneapolis. Over 2,000 people attended from all over the world, including more than 400 Presbyterians and 29 members of the PC(USA) national staff. The conference included presentations by feminist/womanist theologians and feminist rituals.

Days after Re-Imagining ended, critics accused the conference organizers and participants of heresy, witchcraft, and lesbianism. Attention was called to the prayers delivered in the name of Sophia, a personification of wisdom. The Presbyterian Layman published a series of articles on the conference and encouraged churches to call for the resignation of those involved in planning it. The General Assembly Council (GAC) voted to take no action on recommendations to review Lundy’s job. However in May 1994, she was removed from her position. Over fifty overtures were brought to the General Assembly Council Review Committee at the 206th General Assembly. Most overtures asked the Assembly to review the conference and those who organized it, calling for resignations as necessary. The committee instead called for reconciliation which was approved by the General Assembly.

Following the backlash that the conference received, the original organizers mobilized to form the Re-Imagining Community to continue holding ecumenical gatherings and activities in the spirit of the first Re-Imagining conference. The organization published a quarterly newsletter and held six more conferences until it disbanded in 2003. 

After Mary Ann Lundy was removed from her position in the PC(USA), Hartford Seminary named her a Visiting Scholar and Adjunct Faculty Member for a year. She was also nominated to serve a four-year term as deputy general secretary of the World Council of Churches in 1995. Lundy retired in Santa Fe, New Mexico.