Acts 26:26 - Ellicott's Commentary On The Whole Bible

I am persuaded that none of these things are hidden from him. — The appeal to Agrippa’s knowledge is two-fold. He knew that Moses and the prophets had spoken of the great Prophet and Deliverer whom the Jews knew as the Christ. He knew also that for more than a quarter of a century there had been communities of Jews in Judæa and Galilee and Samaria (see Note on Acts 9:31) resting on the belief that the Christ had come, and that He had suffered and risen from the dead. The congregations of those whom the Jews knew as Nazarenes were as far as possible from being an obscure sect lurking in holes and corners.