Carey told The Daily Telegraph he decided to write his new book, "We Don't Do God," after a court ruled in 2010 that an evangelical Christian could be dismissed as a counselor for refusing to work with homosexual couples. Carey wrote the book with his son, Andrew, a journalist.
The book was completed before two more recent court decisions Carey now criticizes. One bans prayers at local council meetings and the other requires bed-and-breakfast operators to give gay couples equal treatment.
"Judges say that the law has no obligation to the Christian faith, but I say 'rubbish' to that," Carey said. "Historically there has been a great interlocking of Christianity with our laws in this country."
Carey said that when he and his wife ran a bed-and-breakfast operation 30 years ago they did rent rooms to gay couples. But he said those who object to homosexuality on religious grounds should be free to do differently.
During his 11 years as head of the Church of England and Anglican Communion, Carey was far quieter than Rowan Williams, who succeeded him in 2002.