In the recently released book: David Flusser, Judaism of the Second Temple Period: Volume 1, Qumran and Apocalypticism (Grand Rapids: Eerdmans, 2007), there is a good article entitled "4QMMT and the Benediction Against the Minim" which includes a brief overview of the societal divisions within Second Temple Judaism. Of particular interest is the Pharisaic sect, a group which (I believe) resembles modern evangelicalism more than any other in Scripture. Thus it is of particular interest to understand this movement and why Jesus was opposed to them so often. (Hint: it is not because they were 'bad' and he was 'good' and we are most certainly on his side, so he can't possibly be talking about us.)
What Flusser points out in his essay is that the name itself began with negative connotations, which were meant as a condemnation of the movement itself - one which the Pharisees could not escape and eventually adopted as their own: "More importantly, the rabbinic Sages came to be called פורשימ, and. . .they were unhappy with this epithet on account of its negative connotations" (93). The charge in question comes from the within the Dead Sea Scrolls (see the title of the article), and is meant to speak against those who separate themselves from the true people of Israel.
It is intriguing, however, that the Qumran sect most certainly were separatist while at the same time condemning those who were separating! The difference is found in the Essene belief that they themselves were the true Israel coming away from apostate Israel. This means that the Pharisees were separating themselves from the true Israel by their actions - in that they were no longer representative of the mission of Israel. Historically, that there was no separatism among the Pharisees demonstrates their ability to capture the popular theological opinion and voice of the day, thus ". . .shaping the course of Jewish history" (98).
Eventually, the primary charge against the Pharisees was that of hypocrisy (cf. 100) - by the Essenes and Sadducess and, most famously, Matthew 23. The case of Jesus is interesting, in that he acknowledges their teaching as coming from the seat of Moses but yet challenges their ability to live it out - an existing authority coming from Scripture, but a failing example. The charge in this situation is that while their words might carry truth, their lives are failure.
In relation to modern evangelicalism, the situation regarding the Pharisees demonstrates the ways in which sub-groups of believers interact with others. The fact that the Pharisees held to a high view of Scripture yet chose to separate themselves from other factions of Israel, yet claim to speak for the whole of Israel is not far from many within the church. It seems that unity among disagreement in the church is not often possible, because we are too quick to ignore or separate from those with whom we may disagree. At the same time, it seems that each group claims exclusivity to the *true* doctrines of God - and that others are apostate.
Addressing the situation outwardly, the church often looks like Pharisees to the world: those who separate themselves (often in stupid or pointless ways), leading to characterizations which are negative but eventually accurate. The die has been cast, but will the end be the same?