Sisk received his B.S. in Economics from The University of Maryland in 1964. He had a call to ministry, and went to The General Theological Seminary in New York City, where he earned his M.Div. in 1967. He later received honorary doctorates from General Theological Seminary, Honorary Doctor of Divinity, in 1984, and Seabury-Western Theological Seminary, in 1998.
He is married to Karen Womack Calvert. They have three children and three grandchildren.
Sisk was a curate for three years at Christ Episcopal Church, in New Brunswick, New Jersey, and a priest for three more years at Christ Episcopal Church in Bronxville, New York. He was then rector of St. John’s Episcopal Church in Kingston, New York from 1973-1977. From 1977 through 1984, he was the Archdeacon of three suburban counties, under the 13th Bishop of New York, Paul Moore. As part of his duties, he started a Japanese congregation, now in Scarsdale, and a Latino congregation in Yonkers.