Born in Detroit in 1930, Gumbleton attended Sacred Heart Seminary High School, and later Sacred Heart Seminary. He then went on to study at St. John's Provincial Seminary in Plymouth, and also the Pontifical Lateran University. He earned a B.A. degree in 1952, a M.Div. degree in 1956, and then later earned a J.C.D in 1964. He was ordained to the priesthood on June 2, 1956, by Cardinal Edward Mooney. In 1968 Gumbleton was made the Vicar General for the Archdiocese of Detroit, and was later named Auxiliary Bishop of Detroit on March 4, 1968. He served as the pastor to a number of parishes including St. Aloysius, Holy Ghost and also at St. Leo's in Detroit until 2007. Gumbleton founded the Michigan Coalition for Human Rights in December 1980 with former Episcopal Bishop Harry Coleman McGehee, Jr. and Rabbi Richard Hertz. Gumbleton's Sunday homilies from St Leo's parish are documented by the National Catholic Reporter, where he also wrote a regular column.
Gumbleton has written extensively on Catholic teaching regarding homosexuality. Gumbleton often draws from his personal experience of having a homosexual brother. During his time as bishop, Gumbleton wore a mitre at a church service on which were symbols of the cross, a rainbow and a pink triangle. The pink triangle caused particular complaints by some due to its history as a symbol of gay rights, after its use to identify homosexuals in Nazi Concentration Camps. Gumbleton also came into the public eye before the Vatican's Instruction with regard to the ordination of homosexual men was released, arguing against Fr. Baker's article on the issue in America.
Resignation controversy
Gumbleton claimed that he was sexually abused by a priest as an adolescent while in the seminary. This attracted some media attention. He stated; "I don't want to exaggerate that I was terribly damaged. It was not the kind of sexual abuse that many of the victims experience", further adding, "They are intimidated, embarrassed, and they just bury it. I understand that", explaining that, "I never told my parents.... I never told anybody." Gumbleton spoke out as a measure to encourage Catholics who have been abused to make complaints through the official channels. Gumbleton was notified that, through his actions in this case, he had violated the solidarity of communio episcoporum in canon law. He said at a conference in 2011 that as a consequence he was forced to give up his position as pastor at St. Leo's in January 2007 and asked to resign from the office of auxiliary bishop. In 2012, Gumbleton signed the Catholic Scholars' Jubilee Declaration on reform of authority in the Catholic Church. Gumbleton was required under church law to submit his resignation when he turned 75. At that time, he petitioned to remain in office.