On "The Two Kingdoms":
The first is the earthly kingdom (in which Calvin includes government, household management, all mechanical skills, and the liberal arts) exists and we exist in it.
The heavenly kingdom (the knowledge of God and of his will, and the rule by which we conform our lives to it) also exists and we exist in it.
It is the separation of these two kingdoms that allow me to be politically and socially active (and not constantly include "as a Christian"...or "as a Reformed Christian") and religiously active (and not constantly feel the need to inject politics into my faith).
I am active in both kingdoms and do not deny either.
When we look to politics for answers to our faith, we are running to the created world (this does not mean that Christians should not be politically active; this means that we should not look to the government to the solutions for our [general "our"; human beings] spiritual questions.
There are those who end up treating radical (or even not so radical) conservatism or liberalism as the "solution" to man's problems. If we only had more money for this program, if abortions were available for any reason, for anybody at any time....and free, if the government would get out of the way, if liberals would get out of the education system, yada, yada...everything would be wonderful!
Man's problem is sin and the solution is Christ.
If a young single high school student gets pregnant, has the kid, lets the government pay for her home, post-high-school education, food stamps, medical care, etc...and then gets pregnant again...and again turns to the government...
the answer to her problem is not to get more government spending. Her problem is her lifestyle and the answer is Christ.
These are the two kingdoms - earthly and heavenly. As Christians, we believe that we are in the world, but not of the world. As members of the earthly kingdom, we can (and should) work to make our physical environment a better place, but we strive for the heavenly kingdom.