He was the 12th bishop ordinary of the Reformed Episcopal Church's Diocese of the Northeast and Mid-Atlantic (NEMA).
[1] He served for 24 years as rector of Grace Reformed Episcopal Church in Collingdale, Pennsylvania, as well as interim rector of St. Mark’s Reformed Episcopal Church in Rydal, Pennsylvania.
Gillin was canon to the ordinary under NEMA bishops Leonard W. Riches and David L.
Co-consecrators were Hicks, Royal U. Grote Jr., Daniel Morse and Richard Lipka.
[2] In 2019, upon Hicks' retirement, Gillin was elected to succeed him as bishop ordinary.