Born into a prosperous Episcopalian (Anglican) family in New Jersey, he received his schooling in Princeton. He then worked as a freelance journalist and, although not an enrolled student, attended some classes at Princeton University and Princeton Theological Seminary. In 1933 he commenced training for the priesthood in the Episcopal Church at General Theological Seminary in New York and in 1937 was ordained priest.

He was awarded the degree of Master of Sacred Theology in 1940, then honorary doctorates in theology by Berkeley Divinity School and General Theological Seminary. For thirty years Pittenger taught theology. From 1952 until his retirement he was Professor of Apologetics. He was also active in many Anglican and ecumenical organisations.

In 1966 he moved permanently to England, where he became a senior member of King's College, Cambridge. Pittenger was an enthusiastic teacher; he loved talking. He wrote more than 90 books. He regarded some of the traditional Christian doctrines as incompatible with modern knowledge; on several occasion conservative Anglicans accused him of heresy. He developed a theology which challenged many of the prohibitions of traditional Christianity.

The first of Pittenger's writings on homosexuality was an essay in 1967, called Time for Consent? A Christian's Approach to Homosexuality. Although ignored by the English church press, it brought him a large correspondence. Time for Consent was notable as the first work in the English language by a prominent theologian that argued the full acceptance of homosexual relationships by the Christian Church.

After the publication of this book, Pittenger became open about his own homosexuality. He established his first long-term gay relationship with Carlo [surname unknown], whom he met in Italy, and quietly supported the gay movement.