This little work is a contribution to American Church History, and to the Centennial Celebration of our National Constitution. It discusses that part of the Constitution which protects us against the despotism of a state church, and guarantees to us the free exercise and enjoyment of religion, as an inherent, inviolable, and inalienable right of every man. The First Amendment is the Magna Charta of that freedom, and well worthy to be set forth in its true light with its antecedents, surroundings, and effects at home and abroad. This I have endeavored to do, for the first time, from the stand-point of a church historian and theologian.<br><br>American Church History has yet to be written. We are so busy making history that we have little time to study and to write history. But monographs on sectional and local topics are multiplying fast, and already present a formidable mass of material for a comprehensive view of the whole field.<br><br>There is scarcely a more inviting task for a rising American historian than to exhibit from the broad platform of truth and justice, in life-like reproduction, the genesis and growth of American Christianity in its connections with the mother Christianity of Europe, its distinctive peculiarities, and its great mission for the future.