Church vs state
The Bible describes a jurisdictional separation between church and state governments. The kings in the Bible were given state responsibilities while the priests were delegated church related responsibilities. The two were to remain separate with specific duties. So, in one sense the mantra about the separation of church and state is legitimate in the sense that God has delegated each with specific duties. The church is not to run the government and the state is not to try and rule over the church. When ever these two government jurisdictions are violated, major problems result.
We see this happening today in America as the state is increasingly moving into the realm of church duties. Moral issues are more and more being dictated by the government, which is the jurisdictional area of the church. The state has taken the role of the church in determining what will be considered moral within the culture and the churches are expected to submit to what ever the state dictates.
This is a tragic occurrence that will eventually lead to a tyrannical state. Liberty requires a constant diligence in maintaining the proper separation between these two jurisdictions.
Government is usually thought of by most people as civil government. However, from the perspective of the Bible there are several government jurisdictions which distribute the power that normally gets accumulated in a state or civil government. By distributing the power of government among several jurisdictions the people are less likely to lose their liberties to a civil state in which much of the political power accumulates. Instead, the political power is broken up and distributed among other governmental jurisdictions that prevent the accumulation of power in the civil sphere. The end-result is an environment in which the people enjoy their liberty and are less likely to be abused by an out of control civil government.