But Baur was a theologian and historian as well as a Biblical critic. As early as 1834 he published a strictly theological work, _Gegensatz des Katholicismus und Protestantismus nach den Prinzipien und Hauptdogmen der beiden Lehrbegriffe_, a strong defence of Protestantism on the lines of Schleiermacher's _Glaubenslehre_, and a vigorous reply to J. Möhler's _Symbolik_ (1833). This was followed by his larger histories of dogma, _Die christliche Lehre van der Versöhnung in ihrer geschichtlichen Entwicklung bis auf die neueste Zeit_ (1838), _Die christliche Lehre von der Dreieinigkeit und Menschwerdung Gottes in ihrer geschichtlichen Entwicklung_ (3 vols., 1841-1843), and the _Lehrbuch der christlichen Dogmengeschichte_ (1847). The value of these works is impaired somewhat by Baur's habit of making the history of dogma conform to the formulae of Hegel's philosophy, a procedure "which only served to obscure the truth and profundity of his conception of history as a true development of the human mind" (Pfleiderer). Baur, however, soon came to attach more importance to personality, and to distinguish more carefully between religion and philosophy. The change is marked in his _Epochen der kirchlichen Geschichtschreibung_ (1852), _Das Christenthum und die christliche Kirche der drei ersten Jahrhunderte_ (1853), and _Die christliche Kirche von Anfang des vierten bis zum Ende des sechsten Jahrhunderts_ (1859), works preparatory to his _Kirchengeschichte_, in which the change of view is specially pronounced. The _Kirchengeschichte_ was published in five volumes during the years 1853-1863, partly by Baur himself, partly by his son, Ferdinand Baur, and his son-in-law, Eduard Zeller, from notes and lectures which the author left behind him. Pfleiderer describes this work, especially the first volume, as "a classic for all time." "Taken as a whole, it is the first thorough and satisfactory attempt to explain the rise of Christianity and the Church on _strictly historical_ lines, i.e. as a natural development of the religious spirit of our race under the combined operation of various human causes" (_Development of Theology_, p. 288). Baur's lectures on the history of dogma, _Ausführlichere Vorlesungen über die christliche Dogmengeschichte_, were published later by his son (1865-1868).