1.
Religious liberty needs the state more than the state needs religion. This I believe. That does not mean that are not intimately related to, one another. Nor does it mean that either is as they should be or will not conflict.
The state is the organization of people of common destiny organized for order, security, and common function. It is the "civil", "civility", civilization: the common good.
It should be no surprise that both state and religion have a common root (for the Christian, it's "man created in the image and likeness of God"): people in communion, in community. In this sense "secular" is as holy as church.
As a Christian, I would summarize this relationship as the companionship of Aristotle and Jesus. Another tradition otherwise. 
Paul not only summarized Jesus message in the most sublime challenge anywhere (Cor.I,13) but he paraphrased Aristotle's sublime text of 500 years earlier, on the essence of ethics, politics and the state (The Nicomachean Ethics). Amazing.