Marie Noonan Sabin, The Gospel According to Mark, New Collegeville Bible Commentary (Collegeville, MN: Liturgical Press, 2006), 7.
Why, then, are the Pharisees vilified in the New Testament? The answer does not lie in the time of Jesus. Indeed, many of the teachings of Jesus are so close to those of the Pharisees that some scholars have proposed that he is shown arguing with them because he was a member of their school. Judaism before the fall of the Temple was tolerant of many different forms of expression, and historical studies suggest that Christianity did not begin as a consciously separate religion, but as a new formulation of the ancient Jewish faith. After the Temple fell, however, Judaism regrouped, and the Pharisaic leaders became less tolerant of diversity within their ranks. In that new atmosphere, Jewish followers of Jesus were regarded with suspicion and put out of their synagogues. The Christian-Jewish community responded with anger. In the context of the post-seventies, the Pharisees appeared hostile to Jesus, and it is that hostility (and their own anger) that the evangelists retroactively projected into their accounts of Jesus’ time.
The Amateur Exegete 