Modern church history naturally falls into four divisions. The distinguishing characteristic of each is found partly in the opposition of particular churches to one another, partly in the antagonism of faith and unbelief. The transition from one to another corresponds generally with the boundaries of the centuries. The =sixteenth century= forms the Reformation period, in which the new Protestantism, parted from the old Roman Catholicism, cast off the deformatory elements which had attached themselves to it, and developed for itself a system of doctrine, worship, and constitution; while the Roman Catholic church, from the middle of the century, set to work upon a counter-Reformation, by which it succeeded in large measure in reconquering the field that had been lost. The =seventeenth century= was characterized on the Protestant side as the age of orthodoxy, in which confessionalism obtained undivided supremacy, deteriorating however in doctrine and life into a frigid formalism, which called forth the movement of Pietism as a corrective; but, on the Roman Catholic side, it was characterized as a period of continued successful restoration. In the =eighteenth century= begins the struggle against the dominant church and the prevailing conceptions of Christianity in the forms of deism, naturalism, and rationalism within both the Protestant and Catholic churches. The fourth division embraces the =nineteenth century=. The newly awakened faith strives vigorously with rationalism, and then, on the Protestant side, splits into unionism and confessionalism; while, on the Roman Catholic side, it makes its fullest development in a zealous ultramontanism. But rationalism again renews its youth under the cloak of science, and alongside of it appears a more undisguised unbelief in the distinctly antichristian forms of pantheism, materialism, and communism, which seeks to annihilate everything Christian in church and state, in science and faith, in social and political life. FIRST SECTION. CHURCH HISTORY OF THE SIXTEENTH CENTURY. I. The Reformation.[360] § 122. THE BEGINNINGS OF THE WITTENBERG REFORMATION.