Professor Schmitz teaches primarily about the history of religions and historical methodology. His research concerns the history of ancient Lebanon, Syria, Palestine (especially the kingdoms of Israel and Judah and their later descendants) and North Africa. He is a specialist in the Phoenician language and the history of Phoenician expansion westward into the Mediterranean prior to Greek and Roman domination of these areas.
Since 1990, he has taught at Eastern Michigan University, first as a lecturer, later as assistant and associate professor. From 1998 to 2002 he served as faculty associate for course and program development in the Academic Affairs division. During academic years 2004–2006 he was interim department head of History and Philosophy. He has recently been an academic service-learning fellow.
Before coming to EMU, he was assistant editor of the Anchor Bible Dictionary and editor of the Index to Book Reviews in Religion. He is a member of the editorial advisory board of Carthage Studies (Ghent) and is currently at work on a Dictionary of Ancient Phoenician Civilization.