Baha'u'llah is the is the Prophet and Founder of the Baha'i Faith. The main theme of Baha'u'llah's message is unity. He taught that there is only one God, that all the world's religions represent one changeless and eternal Faith of God, and that all humanity should live in peace and harmony. 'Abdu'l-Baha is the eldest son and appointed successor of Baha'u'llah, the Prophet and Founder of the Baha'i Faith. 'Abdu'l-Baha shared a lifetime of imprisonment and exile with his father. He spent his entire life in tireless service to the Baha'i Faith, leading the community as an example of constant love, kindness, and humility, and was a lifelong proponent of the unity of all people and religions.