Birger has a B.A in Classical Languages from Upsala College, East Orange, New Jersey; a M.A. in Greek from University of California, Berkeley, California; a Bachelor of Divinity from Pacific Lutheran Theological Seminary in Biblical Studies and Theology, Berkeley, California; and a Doctor of Philosophy in Study of Religion: New testament and Christian Origins from Harvard University.

He has been a professor of religion at many universities/seminaries and has published numerous articles. He is Professor Emeritus at the University of California, Santa Barbara in Religious Studies.