David Bailey Sindt was born in 1940 and grew up attending Presbyterian churches in Minneapolis, Minnesota. He received his Masters of Divinity in 1966 from McCormick Theological Seminary in Chicago and was ordained in 1965 by the Presbytery of St. Paul in the United Presbyterian Church in the U.S.A. (UPCUSA). In 1971, he attained a Masters of Social Work from the University of Michigan and began working for the Chicago Department of Children and Family Services. Also during that year, David began to identify as an openly gay man. He became active in the Chicago Gay Alliance and simultaneously started worshipping at Lincoln Park Presbyterian Church. In 1972, the Session called David to serve as an assistant pastor and establish an outreach program to the local gay community, but this call was rejected by the Presbytery of Chicago in the UPCUSA the following year. This was believed to be the first call ever issued to an openly gay man by a Presbyterian congregation.

Sindt began sending letters to select Presbyterians early in 1974, hoping to seek out people who would be interested in advocating for gay concerns within the Church. These letters initiated the formation of the Presbyterian Gay Caucus (PGC), which met for the first time at the 1974 UPCUSA General Assembly. At that assembly, Sindt held up a sign that said, "Is Anyone Else Out There Gay?" From this action and David's previous grassroots organizing efforts in the months prior to the 1974 General Assembly, a group came into existence at that time known as the Presbyterian Gay Caucus (PGC). The original, proposed name was Gay United Presbyterians (GUP), but since the organizing efforts had always planned to welcome people of all sexual orientations, including heterosexual allies, PGC was chosen instead. Subsequent name changes during the first seven years were as follows: Presbyterians for Gay Concerns (also PGC, 1977), and Presbyterians for Lesbian/Gay Concerns (PLGC, 1980). PLGC remained the name until 1999 when the organization merged with the More Light Churches Network (MCLN) to form More Light Presbyterians which continues its advocacy work today.

After the formation of the PGC, David spent the next five years as the organization’s national coordinator, helping it to establish a network of LGBTQIA+ individuals and allies throughout the church who could support one another as they worked for full membership and ordination rights. He also continued to work for LGBTQIA+ rights in various gay community organizations in Chicago and was an active member of Lincoln Park Presbyterian Church (LPPC). In David's career as a social worker, he helped organize the National Council on Social Welfare Task Force on Homosexuality and the Gay Community, and also organized the Chicago Gay Social Work Task Force, both in 1972. His activism also inspired the LPPC to create a position paper on LGBT ordination rights in 1980, and in 1981 the Session voted to become a More Light congregation. David was diagnosed with AIDS in 1985 and died on December 3, 1986.

During his life, David also became an internationally recognized authority on dwarf irises, and was recognized as an expert hybridizer. Approximately 51 new iris varieties were introduced from his breeding lines, of which 40 were introduced by David during his lifetime. A number of his introductions won prizes in various competitions, and several received the highest awards from the American Iris Society, as well as awards in international competitions. His 1,000 square foot iris garden in the backyard of his home in Chicago contained the largest collection of pumila irises in the world. He became a judge for the Dwarf Iris Society in 1961 and for the American Iris Society in 1969. He later achieved Master Judge status for the American Iris Society. He served as an officer or board member in several iris societies, including being President of the Northern Illinois Iris Society in 1980-81, President of the Dwarf Iris Society in 1981, and Regional (#9) Vice President of the American Iris Society. After David's death, David's parents, Charlotte and Gustave Sindt, arranged to have David's iris stock moved to the Adamgrove nursery in Missouri where, over the next decade, owners Eric and Robert Tankesley-Clarke introduced an additional five varieties from David's breeding program, and introduced an additional six varieties prepared from hybrids created by David of which the Tankesley-Clarkes then selected the final cut of seedlings, named them and introduced them, listing them as Sindt-Tankesley-Clarke varieties.