The Fourth conversation students could choose is a more conventional one for Christians: Doubt.
As you can see these range from classic works to more contemporary life discussions.
Dulles, Avery. Assurance of Things Hoped For
Fischer, John. True Believers Don't Ask Why
Guinness, Os. God in the Dark: The Assurance of Faith beyonf a shadow of a doubt
Hulme, William E. Am I losing my faith?
Lamott, Annie. Plan B: Further Thoughts on Faith
McGrath, Alister E & McGrath, Joanna Collicutt. The Dawkins Delusion? Atheist fundamentalism and the denial of the divine.
Newbigin, Lesslie. Proper Confidence: Faith, Doubt, and Certainty in Christian Discipleship
Smith, Hannah Whithall. The Christian's Secret of a Happy Life - I'm linking this to a current edition as I didn't find a printing which would appeal to students. Even our copy is "old."