The Conflict of Religions in the Early Roman Empire

The Religion of Ancient Rome

Dissertatiunculae Quaedam Critico-Theologicae

The Christian Mythology

Roman Society from Nero to Marcus Aurelius

The Holy See and the Wandering of the Nations, from St. Leo I to St. Gregory I

Historical Sketches, Volume I (of 3) The Turks in Their Relation to Europe; Marcus Tullius Cicero; Apollonius of Tyana; Primitive Christianity

After Life in Roman Paganism

Curiosities of Christian History Prior to the Reformation

The Religious Experience of the Roman People From the Earliest Times to the Age of Augustus

Oriental Religions and Christianity A Course of Lectures Delivered on the Ely Foundation Before the Students of Union Theological Seminary, New York, 1891

Forerunners and rivals of Christianity