Maginnis was ordained a priest for the Archdiocese of Philadelphia by Archbishop John Krol on May 13, 1961.[3] He was a member of the first ordination class ordained by Archbishop Krol.[1] After his ordination, Maginnis was assigned as a curate at Our Lady Help of Christians Parish in Abington, Pennsylvania, where he remained for three years.[2] He then served at Immaculate Heart of Mary Parish in Chester, Pennsylvania, from 1964 to 1967.[2] In 1967, Maginnis was named assistant director of the Archdiocesan Department of Youth Activities.[1] He later became director of the department in 1981, serving in that position until 1988.[1]
In 2004, Maginnis was named head of the Secretariat for Evangelization.[6] He also oversaw the Archdiocesan Metropolitan Tribunal, Chancery Office, the Office for Consecrated Life, the Office for Research and Planning, the Office for Black Catholics, and the Office for Hispanic Catholics.[6]
Retirement
Upon reaching the mandatory retirement age of 75, Maginnis submitted his letter of resignation to the Pope in December 2008.[3] His resignation was accepted by Pope Benedict XVI on June 8, 2010. He was to continue to administer confirmations in Chester and Delaware Counties, and spend the rest of his retirement reading and studying.[7] He was replaced as an auxiliary bishop by Monsignor John J. McIntyre.[7]
Maginnise died at Villa Saint Joseph in Darby, Pennsylvania after suffering a lengthy illness. His funeral is due to be held at the Cathedral Basilica of SS. Peter and Paul. Nelson J. Perez, Archbishop of Philadelphia, paid tribute to Maginnis as a "man of great joy and charity" who possessed the "true spirit of a missionary disciple".[8]