Christian engagement with nonbelievers is problematic when believing itself proves difficult
even for people of faith. A recovery of the original unity of the fides quae (the “content” of
faith held in belief) and the fides qua (how faith’s content is lived) can lead to a deeper sense
of believing. Rahner’s understanding of faith as a “mystagogy” that leads to mission serves
as a framework for recovering that original unity, and for addressing the contemporary
problem of belief, not only for nonbelievers, but also for believers themselves.