At some significant sacrifice to his family, he was enrolled in a Jesuit boarding high school in St. Mary's, Kansas, where he came first in his class three out of his four years there.

John McKenzie taught for nineteen years at the Jesuit Theologate in West Baden, Indiana, before transferring to Loyola University Chicago.

[citation needed] At the time of its publication in 1956, a review in the periodical The Thomist called McKenzie's The Two-Edged Sword "the most significant Catholic interpretation of the Old Testament ever written in English.

He is the author of a number of articles in the Encyclopædia Britannica (14th edition): Adam and Eve, Hexateuch, Israel, Mizpah, Pentateuch, Zephania, and Zion.

Testimonials to his work include a comment by Dorothy Day, who wrote in her diary, "Up at 5:00 and reading The Power and The Wisdom.