As a newly baptized Lutheran, his interest in Christian doctrine and theology eventually led him to Yale Divinity School where he met his wife, Sandy.
After graduating from Yale and teaching for many years at St. Olaf College and Southern Methodist University, in 2005, Marshall converted to Roman Catholicism - a decision fostered in part by the success of the Lutheran-Catholic dialogues taking place at the time.
Boyd Taylor Coolman has similarly expressed, "Bruce Marshall is a theologian of the highest caliber, of remarkable depth and breadth, of historical sources and of systematic coherence, of scientific rigor and sapiential insight, of Scripture and philosophy, of Israel and Church, of faith and reason, of love and knowledge.
"[9] The late Geoffrey Wainwright called Marshall's Trinity and Truth "remarkable," [10] and Paul J. Griffiths proclaimed it "a splendid example of how Christians should think about philosophical questions.
[12] Similarly, the journal Pro Ecclesia published a symposium in which Marshall's assessment of the theology of Karl Barth anchored the conversation.