The work Ἰωσήππου βιβλίον Ὑπομνηστικόν, or is devoted chiefly to the removal of such doubts or difficulties as might occur to less instructed Christians in reading the Scriptures, and is usually divided into five books, and 167 chapters. Chapter 136 is an extract from Hippolytus of Thebes [HIPPOLYTUS, No. 3], interpolated, as Cave supposes, by a later hand. This extract inclined Fabricius, who was not disposed to regard it as an interpolation, to place the writer in the eleventh century; and it was probably the same reason which induced Gallandius to assign to the work the date A. D. 1000. But the editor of the last and posthumous volume of the of Gallandius supports the conclusion of Cave as to the earlier existence of the writer, whom, however, he identifies with Joseph of Tiberias.

The materials of the work are chiefly taken from Flavius Josephus, who is once or twice cited by name; and Cave suspects that the work was originally anonymous, and that the name of Josephus indicated, not the author's name, but the source from which he borrowed his statements ; but that being mistaken for the author's name, he received the designation of Christianus, by way of distinction from Flavius Josephus.