At Princeton Forster majored in economics, but his life work became teaching and pastoring in human potential and spiritual growth, building upon Christian and other faith traditions. He and his wife, Julia, founded and led many Christian church congregations and other groups in a variety of locations across the United States. He earned theological degrees from Union Theological Seminary in 1951 and from Weston Jesuit School of Theology in 1984. He was ordained as a Presbyterian pastor and had joint standing as a pastor in the United Church of Christ.

Forster and Julia maintained that they gained much insight and understanding through Eastern mysticism and natural foods and from participation in the civil-rights movement of the 1960s — “clues about human transformation and spiritual potential that the New Testament authors talked about.”

Forster died Nov. 5, 2019, in Portland, Ore., at age 92. He was predeceased by Julia in December 2009. Forster is survived by their five sons, two daughters, six grandchildren, and nine great-grandchildren.