Federalism is a political concept in which a group of members are bound together by covenant (Latin: foedus, covenant) with a governing representative head. The term "federalism" is also used to describe a system of government in which sovereignty is constitutionally divided between a central governing authority and constituent political units (such as states or provinces). Federalism is a system based upon democratic rules and institutions in which the power to govern is shared between national and provincial/state governments, creating what is often called a federation. Proponents are often called federalists. Federal headship refers to the representation of a group united under a federation or covenant. For example, a country's president may be seen as the federal head of his nation, representing and speaking on its behalf before the rest of the world. In Christianity, this concept has been used to explain the concepts of the covenants found in the Bible. In particular, it has been applied to passages such as Romans 5:12-21, explaining the relation of all humanity with Adam, as well as the relation of redeemed humanity with Jesus Christ, who is called the last Adam. According to this understanding, as humanity's federal head Adam brought the entire human race into sin, misery, and death due to his disobedience. Christ,
in his perfect obedience to God the Father, earned eternal life and blessedness for all his people. These concepts can be found in the writings of the Church Fathers, including Irenaeus' Against Heresies and Augustine's City of God. The full theological articulation came in the time of the Protestant Reformation, and this doctrine is held by many Protestant churches, particularly in Presbyterian and Reformed churches. Sovereignty is the quality of having independent authority over a geographic area, such as a territory. It can be found in a power to rule and make law that rests on a political fact for which no pure legal definition can be provided. In theoretical terms, the idea of "sovereignty", historically, from Socrates to Thomas Hobbes, has always necessitated a moral imperative on the entity exercising it. For centuries past, the idea that a state could be sovereign was always connected to its ability to guarantee the best interests of its own citizens. Thus, if a state could not act in the best interests of its own citizens, it could not be thought of as a УsovereignФ state. The concept of sovereignty has been discussed throughout history, from the time of the Romans through to the present day. It has changed in its definition, concept, and application throughout, especially during the Age of Enlightenment.