In 1967 he accepted a call to the Evangelical Lutheran Theological Seminary in Columbus, Ohio, USA, now Trinity Lutheran Seminary, first as Instructor for Systematic Theology, then Assistant and Associate Professor and finally as the first Edward C. Fendt Professor of Systematic Theology, a newly endowed chair.
1967 folgte er einen Ruf an das Evangelical Lutheran Theological Seminary in Columbus, Ohio, USA, jetzt Trinity Lutheran Seminary, zunächst als Instructor for Systematic Theology, dann Assistant und Associate Professor und schließlich zum ersten Inhaber der Edward C. Fendt Professur für Systematische Theologie.