Paul Tillich was born in 1886 in Starzgeddel, Germany, and died in Chicago, Illinois, in 1965. His father was a Lutheran pastor and young Tillich followed his father's path. He got his PhD at the University of Breslau and studied theology at the University of Halle-Wittenberg. 

Tillich's views on theology were controversial. He argued that religion was corrupted by capitalism and its self-interest and needed an infusion of socialism to address the spiritual and daily lives of those who sought religion as a guide. He was fired when the Nazis came to power, and at age 47 he learned English and took a job at Union Theological Seminary in New York. He also taught at Harvard and at the University of Chicago. 

He applied existential philosophy to theology and argued that God was beyond being an essence or existence. He claimed that "being" was the basis for religion because it was expressed through the self, freedom, causality, space, and substance. He designated that involvement as "ultimate concern." His popular book, The Courage to Be, expresses this existential approach to religion. Among UUs it relates to our commitment to social action and justice as part of our ultimate concern. His critics interpreted him as a pantheist (like Spinoza) or as an atheist who abandoned a personal God.