John Duff

Division Chair, Associate Professor of Historical and Systematic Theology

Staff Positions

  • Traditional Undergrad Academics / Bible, Religion & Ministry
  • Grand Rapids Theological Seminary / Bible, Religion & Ministry


Ph.D., Calvin Seminary

M.T.S., Grand Rapids Theological Seminary

M.A., Western Kentucky University

B.A., Cedarville University



Phone: 616-254-1650 ext. 1202

About John

Field(s) of Study/Expertise

Systematic and historical theology with a special emphasis on eschatology of the 17th century.
Apologetics and religious epistemology.

Why teach theology?

Everyone is a theologian. Professor Duff knows this because every semester he teach dozens of students who, though having had no previous class in theology, arrive with very distinct beliefs about God—beliefs about who God is, what God has done in the past and what God is doing now. Often these beliefs lack clarity and precision; nevertheless, these beliefs are firmly held and provide direction for students in the ebb and flow of their lives. These students are indeed theologians, holding a vast array of beliefs about God and the world.

Although every student is already a theologian, it is his hope that they will become better ones. It is Professor Duff's privilege to help students unpack their beliefs and examine what they believe and why they should believe it. Improvement as a theologian is at least partially an intellectual exercise. Hence, Professor Duff and his students work diligently to ground Christian beliefs in God’s written revelation—the Bible, to state them as accurately as we can, to eliminate incoherent or contradictory beliefs and to understand why there is some diversity of beliefs among Christians about some issues. These tasks can be arduous, unsettling, and sometimes perplexing; they also can be simple, affirming and clarifying. But they are important tasks to undertake, because the most important thoughts a person can ever have are thoughts about God.

Yet improvement as a theologian is more than an intellectual exercise; it is a moral exercise as well. Christian theology was never intended to merely help students think well but also to live well. It should never become an intellectual club that is wielded in order to win arguments; it should be food that nourishes the soul so that we may grow in faith, hope and love. As Christian believers, we are to grow in grace and in the knowledge of our Lord and Savior, Jesus Christ.

Profesor Duff enjoys woodworking, basketball, golf, reading historical fiction, and landscaping. He spent 10 years in church ministry serving as a worship leader and a teaching pastor before arriving at Cornerstone.