In 1980 he was appointed a member of the Historic Monuments Council for Northern Ireland (now part of the Department for Communities) and was chairman from 1988 to 1995.

Pursuing a vocation to the ministry, Harper entered the Church of Ireland Theological College in Dublin in 1975 and was ordained a deacon in 1978 at St Anne’s Cathedral, Belfast.

[citation needed] He later served as vicar of Moville, followed by a tenure as rector of Christ Church, County Londonderry from 1982 to 1986.

[citation needed] Since issues of sexuality (particularly homosexuality) are the topic of endless debate and simmering acrimony in the Anglican Communion at present, Harper's election to the primacy immediately drew media interest to his views on these questions; previous interviews were given new scrutiny.

Several commentators[10][11] concluded that he is personally liberal but willing to be bound by more traditional views as long as the Church of Ireland has not as a whole signaled a desire for change.