When a community of stable societies over a particular region is divided into two classes: a ruling class and another that is governed, the state appears, and this division usually occurs as a result of the possession of a member of the community or a class of one of its classes of a factor or more of the factors of power, whether that power is a power Economic, military, or ideological, which helps the powerful group to consolidate its influence and subject the rest of society to its rule and political authority.
History tells us that the state has existed since prehistoric times. Its oldest and most prominent form was the "city-state" that flourished in Mesopotamia, Egypt and Greece, and was the nucleus from which the nation-states and empire arose after that.
But the legal concept of the state, as a group of individuals inhabiting permanently and in stability in a specific geographical region and subject to the organization of its affairs to a political authority independent of the rulers who practice it, was only known in modern times. The concept of the state in Greece was confined to the framework of the city-state, Polis. The Greek philosophers, such as Plato and Aristotle, did not distinguish between the state on the one hand and society on the other hand, but the state and society were the same.
And when Christianity appeared and began to broadcast the saying of Christ, "Let Caesar be for Caesar and God is for God," the signs of separation between the state and religion began to appear, because the work of this directive requires that the Church be concerned with the affairs of directing religion and leave the state to take care of matters of governance and the application of laws. Had this been done, it would have led to a distinction between the concept of the state and society.
But what happened is that the power struggle between the state and the church intensified strongly because the churchmen believed that they are responsible before God for directing society and the state according to the teachings of religion. One of the results of this conflict was the submission of the state at times to the ranks of the church and the submission of the church to the authority of the state at other times until the outcome of the conflict was stabilized in favor of the state.