[2] He continued to work as a barrister specializing in religious freedom cases in international Human Rights law until his death.
[12] Montgomery was a scholarly maverick[13] who earned eleven degrees in multiple disciplines: philosophy, librarianship, theology, and law.
[17] In 1959–60 he served on the faculty of theology as principal librarian in the divinity school's library at the University of Chicago, while simultaneously undertaking doctoral studies in bibliographical history.
[18] He then served as chairman of the Department of History at Wilfrid Laurier University in Canada, where he began to develop a reputation as a Christian apologist.
[19] On receiving a Canada Council Senior Research Fellowship, Montgomery commenced doctoral studies in theology at the University of Strasbourg, France.
His doctoral dissertation, which was on the life and career of the Lutheran pastor Johannes Valentinus Andreae and his alleged connections with Rosicrucianism, was subsequently published as Cross and Crucible.
[20] After completing his Th.D in 1964, Montgomery assumed a post as professor of church history at Trinity Evangelical Divinity School in Deerfield, Illinois (1964–1974).
It was during the 1960s that he emerged as a significant spokesman for Protestant Evangelicals, writing as a regular columnist in the flagship periodical Christianity Today (1965–1983).
On the wider church scene he wrote against the Death of God theology, and publicly debated one of its proponents, Thomas J. J. Altizer, at the University of Chicago in 1967.
[31] The same year, Montgomery and Michael Richard Smythe founded the Irvine, California-based Institute for Theology and Law which, in 1995, became the current International Academy of Apologetics and Human Rights in Strasbourg, France.
[32] In 1991, Montgomery relocated to London, where he became a Barrister-at-Law,[33] wrote widely on apologetics, defended international cases of religious freedom, and taught at the University of Bedfordshire.
[34] Montgomery's apologetic work generally centered on establishing the divinity of Christ by assessing the historical and legal evidences for the resurrection.
[35] Much of this work has influenced popular apologists such as Josh McDowell, Don Stewart, Francis J. Beckwith, Ross Clifford, Terry Miethe, Gary Habermas, Craig Parton, Rod Rosenbladt, Loren Wilkinson, Kerry McRoberts, and Elliot Miller.
He wrote on legal-moral problems such as cryonics, stem-cell research, euthanasia, abortion, and divorce, and also argued for a transcendental perspective in international human rights and jurisprudence.