The BSA allowed gay youths full participation in 2014 and openly gay adults as leaders in 2015. It is a common belief that the BSA does prohibit members who are atheist and agnostic based on its "duty to God" principle and that members (adult and youth) agree with the Declaration of Religious Principle in the bylaws. However, the BSA has had Buddhist troops since 1920, and many Buddhists are atheists or agnostics. The BSA also signed a Memorandum of Understanding with the Unitarian Universalist Association in 2016 which specifically gives ultimate authority over a participant's spiritual welfare to the individual Unitarian Universalist congregation. The MOU also specifically includes within Unitarian Universalist chartered troops Humanism as an acceptable form of spirituality as well as Earth-centered religions.