[2][3] He is also Emeritus Professor of Theology at Xavier University in Cincinnati, where he taught for 28 years before moving to Union.

Knitter received permission to leave the priesthood in 1975, becoming a professor of theology at Xavier.

[7] Along with his friend and colleague, the Protestant philosopher of religion John Hick, Knitter came under criticism of Cardinal Joseph Ratzinger, then-prefect of Congregation of the Doctrine of the Faith and later Pope Benedict XVI, for "relativism.

"[9] Robert Magliola criticizes Knitter's proposed "one universal Spirit" concept, asserting that it perpetuates the modernist idea of "equable holism" or "openness" (the "modern idol") rather than the "jagged, asymmetrical" nature of reality.

[10] Critiquing Knitter's views on religious double belonging, Joseph A. Bracken argues that "in ethical reflection one should begin with the recognition of the Otherness of the Other" rather than with "the sustained meditation by the self on one's moral responsibility for others":[11] In a review of Jesus and Buddha: Friends in Conversation, Magliola critiqued Knitter and Roger Haight's discussion of the possibility of double belonging in Catholicism and Mahayana Buddhism.