The Archbishop began his final Easter sermon arguing that young people's hostility towards faith is not as extreme as society perceives it to be.
He said that many young people take the issue of religion seriously, despite not attending Church.
He warned that now was the "worst possible moment" to downgrade the importance of teaching religion in secondary schools.
Dr Williams, who will take up a post at Cambridge University in January, also told followers that the ultimate test of the Christian religion is not whether it is useful or helpful to society but whether or not its central claim - the resurrection of Jesus Christ - actually happened.
Dr Williams' ministry has been challenging at times. Under his leadership, the Church of England nearly split over the ordination of gay clergy and women bishops.
Dr Williams has shown no resistance to the appointment of openly gay bishops, as well as showing continued support for the ordination of women.
He will continue to carry out all the duties and responsibilities of the Archbishop of Canterbury, both for the Church of England and the Anglican Communion, until the end of the year, Lambeth Palace said.