He then returned to Philadelphia to serve at the historic Tenth Presbyterian Church in from 1961 to 1967. He returned to pastoral duties at Knox Spadina in Toronto, Ontario, where he was an Elder before becoming Interim Minister in 1987; and Senior Pastor from 1989 to 1992. In 2000, he retired to Ottawa where his son-in-law was a pastor. He also taught at Tyndale University College and Seminary(then known as Ontario Theological Seminary) ; and was named Professor Emeritus in Pastoral Theology. He served as the Canadian and North American Director of a missionary agency called Interserve (formerly Bible and Medical Missionary Fellowship) from 1967 to 1988.
He was designated an "Evangelist-at-Large" within the Presbyterian Church in Canada during the 1970s and 1980s, and hosted a radio broadcast Amazing Grace, sponsored by Presbyterian Men, and broadcast on a few stations, and also participated on other radio ministries in both Canada and the United States.
He was also active in the formation and early years of the Evangelical Fellowship of Canada and served for two years as that organization's president from 1969.[4] He was also a popular preacher, who preached at many special services, including Anniversaries, conferences (such as Urbana 84),[5] and at Evangelistic Meetings particularly in Canada, the US, and in Italy. He was also involved in the formulation of papers connected to the Lausanne Covenant.[6]
Di Gangi authored many books dealing with the Christian faith, including A Golden Treasury of Puritan Devotion: Selections from the Writings of Thirteen Puritan Divines, Twelve Prophetic Voices, The Book of Joel: A Study Manual, and The Spirit of Christ.
A chapter in Tenth Presbyterian Church of Philadelphia: 175 Years of Thinking and Acting Biblically by Philip Ryken deals with Di Gangi's pastorate of that church, where he was preceded by Donald Grey Barnhouse and succeeded by James Montgomery Boice.
The happy people: discovering our Lord's secret of real happiness as revealed in His Beatitudes. Agincourt, Ontario: Bible & Medical Missionary Fellowship, c1976.
Reaching the unreached: a report on the Canadian Consultation on Evangelism. Agincourt, Ontario: BMMF International/Canada, 1983.
Life and immortality. Agincourt, Ontario: Bible & Medical Missionary Fellowship, 1975.
The sufferings and the glory: a devotional study of the 22nd Psalm. Agincourt, Ontario: Bible & Medical Missionary Fellowship, [197-].
The meaning of Christian discipleship. Agincourt, Ontario: Bible & Medical Missionary Fellowship, 1975.
A living church: compared to what the Bible says about a living church, is yours alive or in need of revival? Agincourt, Ontario: Bible & Medical Missionary Fellowship, [197-?].
Peter Martyr Vermigli 1499-1552: Renaissance Man, Reformation Master. Lanham, MD: University Press of America, 1993.