An Agnostic's Apology and Other Essays (Barnes & Noble Digital Library‪)‬

In addition to the title essay, this 1893 collection contains "The Scepticism of Believers," "Dreams and Realities," "What is Materialism?", "Newman's Theory of Belief," "Toleration," and "The Religion of All Sensible Men."  Stephen asserts that theological matters are beyond the grasp of human reason, and so it is fruitless to speculate upon them.