Yesterday in Public theology we had a christian brother come in from here to share with us his view on how Christians should relate to the public square. The model he goes for is called 'Principled Pluralism.' This position states that under every circumstance, the ideal is that states are 'confessionally silent'. This does not mean 'we don't do God' in the sense that christian politicians must leave their christianity at home when they head to westminster, but rather that the state must never officially enshrine one epistemology (faith, worldview, etc.) in its constitution as the basis for legal authority (why it has put in the statute book what it has). Christians can and should let their faith inform their political opinions and actions, but the state must never favour Christianity in its constitution.
PP advocates believe that this is the way that God wants the state to be, because it must represent and govern all of its people, and does not have the right to impose faith on anyone.
The problems with such a view are manifold;
1.Of course the state can't impose faith on anyone, and shouldn't try. But, this is not the same as the state overtly basing it's laws on a particular worldview or faith. The minute the state legislates anything, it is imposing values derived from a worldview.
2. There is no such thing as confessional silence. Unless you are going to have a completely blank constitution that is (see below). Once you have a constitution you have taken a side, even if that side is 'we think every/no religion is right' or 'we think the government should always do what the majority says' or 'we think the government should rule for the common good'.
3. A blank constitution is a bad idea, since it means having a government exercising power based on no authority at all. Naked power without a basis for authority is a very bad thing.
4. A constitution based on something other than Jesus being Lord is an idolatrous constitution - it says something/one is Lord other than Jesus Christ.
5. Saying that 'Jesus is Lord' can never be in the constitution amounts to 'we don't do God' in our constitutions. Since Jesus really is Lord of all things and everyone, this surely includes constitutions.
Paradoxically, PP adovocates affirm that God requires the state to rule justly as his servant. So, we are left with the following statements about what God wants of the state.
a. God requires the state to govern as his servant, ruling justly, punishing evil and commending good, within the jurisdiction given to it by God.
b. God requires the state to never ever own up in public or state in its constitution that a. is true.
You can look here for where I stole most of the thoughts above from.