His academic career began at Bond University on Australia's Gold Coast, where for a number of years he was professor of history and philosophy.

[1][2] During his time at Oxford, he was a fellow of Harris Manchester College and director of the Ian Ramsey Centre where he continues to hold a senior research fellowship.

He delivered the 2011 Gifford Lectures at the University of Edinburgh[3] published as The Territories of Science and Religion and named winner of the 2015 Aldersgate Prize.

[7] In 2017, Harrison demonstrated that the Credo quia absurdum was a quote misattributed to Tertullian in the early modern period as a part of anti-religious and anti-Catholic polemics.

This historically contingent distinction, he proposes, might be a key premise of contemporary naturalism but is not, on most traditional understandings, requisite for religious commitment itself.