Do you think a republic or a monarchy can have a complete wall between church/religion and state? I don't. I think republics and monarchies can maximize a wall, but it can't be complete. Basically, I was thinking the only way to have a true wall between church/religion and state is to have a confederation (although then I don't think the republics or monarchies that form the confederation are able to have a complete wall between church/religion and state) or to not have any state at all.
What are some good works on the topic?
I think an autarchy provides a complete wall between C&S.
Please clarify what you mean. Usually when this is brough up this can mean one or more of the following:
1. Church and state as separate institutions in terms of the one being independ from the other financially and directively. With other words no theocracy (like in the vatican) or state church (like in Sweden).
2. Keeping religious convictions out of policy and law making.
3. Preventing the state from intervening into church or religious affairs.
There are some nuances to all of those. I personally have a preference for those institutions to be independent from each other. That means the government operates towards it's own guidelines with it's own budget and limited authority and mode of operation. And the church is just another voluntary association of grown ups perhaps including their children. I think this would be covered by 1 and 3 to some extent.
No.2 is of course a pure thought construct, since any political conviction does have some religious underpinings (including atheism, agnosticism, materialism or secularism). Also, religion is a field where morality and cosmology are formed, and this will influence how people form political thought.
For me this all isn't really a problem, since I am a social pluralist. In my conception of political society different communities can cluster and make their own rules according to which they wish to live. An individual would then have the choice to either join or leave a community.
All 3, but never able to be for forced secularism/forced Atheism.
There should not be a separation of church and state, there should not be a state period to intermingle with a church. Any question of a separation between church and state is silly because it assumes the state has so far penetrated civil society that it is intermingling with religion. The way to separate church and state is to separate the state from the daily lives of people and this "separation" will cease to be an issue.
I do not think the State and religions should mingle. I do not think they should be enemies either. A secular democracy will replace the worship of God with the worship of the State. A monarchy is essentially the same structure as a church, so that is a given.
You could read
Tocqueville's Democracy in America. He talks a lot about the various aspects of religious values in politics throughout the whole thing.
Rousseau, Social Contract, Bk IV, Ch. 8 - a bit where he actually makes sense.
Machiavelli, The Prince - He talks about how leaders of religious institutions can live however they want due to the institutions existence.
Federalist No. 18 discusses "Ancient Confederations." There might be something you find useful about confederations, 'temples', and how they correlates to republics.