-- Acts 15:1-6
Among the religious authorities of Jerusalem, not only were the Pharisee Nicodemus and the prominent Joseph of Arimathea both secret disciples of Jesus, but there was also long-standing dissension about him, so much so that St. John says of these authorities on the very eve of Christ's Passion, "many.. . believed in him", though very imperfectly. This is not surprising, if one recalls that on the day after Pentecost "a great many of the priests were obedient to the faith" and "some believers. . . belonged to the party of the Pharisees", to the point that St. James could tell St. Paul, "How many thousands there are among the Jews of those who have believed; and they are all zealous for the Law."
-- CCC 595