Tietjen was born in New York City as a son of German immigrants, and he attended Stuyvesant High School, Concordia Collegiate Institute (now Concordia College, Bronxville), and Concordia Seminary in St. Louis, Missouri. He also earned master's and doctorate degrees at Union Theological Seminary in New York. After being ordained in the LCMS in 1953, Tietjen rose through the Synod ranks and eventually was chosen as president of its largest seminary, Concordia Seminary, in 1969.
