Cox was ordained as an American Baptist minister in 1957, and started teaching as an assistant professor at the Andover Newton Theological School in Massachusetts. He then began teaching at Harvard Divinity School (HDS) in 1965 and in 1969 became a full professor. He was to become “the single most heeded professor in religion at Harvard.”[6]
Cox became widely known with the publication of The Secular City in 1965. It became immensely popular and influential for a book on theology, selling over one million copies. Cox developed the thesis that the church is primarily a people of faith and action, rather than an institution. He argued that “God is just as present in the secular as the religious realms of life”.