I had a friend ask why, according to NT Wright, Jesus rebuked the Pharisees. I gave this response:
The Pharisees were, according to Wright, as concerned with the need for a political solution of purity as well as the religious, which I think is important to remember. In the ancient world religion and politics were explicitly mixed, whereas today it is more implicit or at least mostly on the level of rhetoric rather than practice. Thus when Jesus was preaching the Kingdom of God, the Pharisees could easily get on board with that as a restored kingdom of Israel, which entailed kicking out all the impure gentiles much like had happened with the Hasmoneans and the Hanukkah story. However, the way that Jesus went about bringing in the kingdom was not through rebellion, which didn’t fit with the Pharisaic mindset of zeal for purity. Rather, Jesus’ vision included not only the impure Jews as included in the kingdom but also the (really) impure Gentiles.
NTW in his own words on this:
the rigorous application of the law in the way we have observed, as a defence against Gentiles and hence as a reinforcement of national boundaries and aspirations, had become, in Jesus’ view, a symptom of the problem rather than part of the solution. The kingdom of the one true god was at last coming into being, and it would not be characterized not by defensiveness, but by Israel’s being a light to the world; not by the angry zeal which would pay the Gentiles back by their own coin (as Mattathias had advised his sons), but by turning the other cheek and going the second mile. The command to love one’s enemies, and the prohibition on violent revolution, constituted not an attack on Torah as such but a radically different interpretation of Israel’s ancestral tradition from those currently on offer. Jesus, precisely in affirming Israel’s unique vocation to be the light of the world, was insisting that, now that the moment for fulfilment had come, it was time to relativize those god-given markers of Israel’s distinctiveness. (Jesus and the Victory of God, 389)