Ullmann was born at Epfenbach, near Heidelberg on the 15th of March 1796. He studied at Heidelberg and Tubingen, and in 1820 delivered exegetical and historical lectures at Heidelberg. In 1829 he went to Halle as professor to teach church history, dogmatics and symbolics, but in 1836 he accepted a chair at Heidelberg.
A lifelong exponent of the mediating theology (Vermittelungs-Theologie), in 1828, with the help of Umbreit (1795-1860), he founded and edited the Theologische Studien and Kritiken in its interests. When Wegscheider and Gesenius were denounced by Hengstenberg as rationalists, he pleaded for freedom in theological teaching (cf. his Theol. Bedenken, 1830). On the other hand, he vigorously attacked David Strauss. His Historisch oder mythisch (1838; 2nd ed. 1866) was a reply to Strauss's Life of Jesus, and his criticism resulted in Strauss making numerous concessions in later works. Ullmann died on the 12th of January 1865.
In Das Wesen des Christenthums (1845; 5th ed., 1865; Eng. trans., 1860) Ullmann explains that Christianity is independent of the orthodox formulas, and contends that a distinction should be made between faith and dogmatics. His principal historical works are Gregor von Nazianz (1825; 2nd ed., 1867) and Die Reformatoren vor der Reformation (2 vols., 1841; 2nd ed., 1866; Eng. trans., 1854). Another well-known work is Die Siindlosigkeit Jesu (1854; Eng. trans., 1858 and 1870).