A lthough the emergence of the secular state is a phenomenon of modern history, the concept of the secular state reaches back through the centuries. However, throughout its history, until the modern era, the idea of the secular state has been uniquely related to the history of Christianity and the state. Inherent in the view of the secular state is the clear separation of the spiritual and temporal powers. The basis of the authority of the state is civil and natural law, not religious decree or divine law.
Surely, one of the major architects of the concept of the secular state was Marsilius of Padua, the renowned Catholic thinker of the fourteenth entury. In his great treatise, Defensor pacis, published in 1324, Marsilius vigorously challenged the claims of the supremacy of the church over the state and likewise rejected the notion of the Christian state ormundus Christianus. In this work he made a sharp distinction between divine and human law. He insisted that the state be based upon law inherent in nature, and that the church should not have jurisdiction over the state. Clearly ahead of his time, Marsilius held that
Laws derive their authority from the nation, and are invalid without its assent. As the whole is greater than any part, it is wrong that any part should legislate for the whole; and as men are equal, it is wrong that one should be bound by laws made by another. But in obeying laws to which all men have agreed, all men, in reality, govern themselves.... He (the monarch) is responsible to the nation, and subject to the law; and the nation that appoints him and assigns him his duties, has to see that he obeys the Constitution, and has to dismiss him if he breaks it.