Ernst Troeltsch (17 February 1865 – 1 February 1923) was a German Protestant theologian and writer on philosophy of religion and philosophy of history, and an influential figure in German thought before 1914. His work was a synthesis of a number of strands, drawing on Albrecht Ritschl, Max Weber's conception of sociology, and the Neo-Kantians of the Baden school.
His The Social Teachings of the Christian Church (two volume edition in translation by Harper Row, 1960) is a seminal work in this area.
While religious thinking in the days of the Weimar Republic moved away from his direction, Troeltsch's work in the sociology of religion remains important.