Jacob’s research focuses on the question of what it means to have faith and what having faith entails. Related questions include: the manner in which historicality conditions transcendence, especially in a modernity that is both technological and secular; how desire and habit affect our relations to ourselves, God, and one another; what kind of knowledge we can have about God; and what a moral judgement can be for a believer.

Many different interlocutors have helped Jacob pursue these lines of inquiry. Foremost among them is Martin Heidegger, but also Charles Taylor and Terrence Malick. Others include: Augustine, Eckhart, Luther, Pascal, Kierkegaard, René Girard, Harry Frankfurt, the Pittsburgh school of philosophy, and, increasingly, R.S. Thomas.