In his works, especially in his investigation into the sources of the New Testament, Bauer concluded that early Christianity owed more to ancient Greek philosophy and Stoicism than to Judaism. By 1840, Bauer had begun arguing that Jesus was a 2nd-century fusion of Jewish, Greek, and Roman theology, saying (Synoptiker), “We save the honor of Jesus when we restore His Person to life from the state of inanity to which the apologists have reduced it, and give it once more a living relation to history, which it certainly possessed.” Bauer himself was never an orthodox Christian. Between 1850 and 1852 Bauer published more historical and literary criticism on the Bible: Kritik der Evangelien und Geschichte ihres Ursprungs (A Critique of the Gospels and a History of their Origin), as well as Kritik der paulinischen Briefe (Critique of the Pauline Epistles). These were followed in 1877 by Bauer’s last book on theology, Christus und die Caesaren (Christ and the Caesars).
Considered one of the leading German Biblical critics of the 19th century, and claimed by both the left wing and the right wing of the Hegelian school, by the end of his life Bauer was spurned by both parties. The former teacher and friend of Karl Marx, he broke with Marx and Frederick Engels over their socialism and communism, later associating with Max Stirner (1806-1856) and Friedrich Nietzsche. Bauer never married, but he continued to write books to the end of his life, self-publishing and supporting himself through work in his family’s tobacco shop. Bruno Bauer died in Berlin on 13 April 1882 at age 72. Justifying his Rationalist approach to biblical scholarship and criticism, it was Bruno Bauer who said (1842), “Reason is the true creative power, for it produces itself as Infinite Self-consciousness, and its ongoing creation is … world history.”