Complex sentence: It is grounded in the belief that there is only one source of authority to which Christians are ultimately answerable, the authority of God as embodied in the teachings of Jesus, and thus rejects the idea that human governments have ultimate authority over human societies.
Split into simpler sentences: It is grounded in the belief that there is only one source of authority to which Christians are ultimately answerable--the authority of God as embodied in the teachings of Jesus. It therefore rejects the idea that human governments have ultimate authority over human societies.