Richard Beck's wonderful book Unclean: Meditations on Purity, Hospitality, and Mortality. This discussion is rooted not only in the book, but Richard's presentations at the recent Streaming Conference at Rochester College.
Entitled Mercy not Sacrifice the conference took as texts Matthew 9 and Matthew 12, where Jesus comes down on the side of mercy rather than sacrifice (following in the footsteps of Hosea 6:6). In his book, Beck discusses the ways in which we deal with matters of purity, suggesting that in emphasizing purity, the Pharisees found themselves pulling away from "sinners." Jesus, on the other hand, emphasizing mercy reaches out to sinners and brings them into fellowship.
In our own time and place, we wrestle with these same kinds of issues -- purity/sacrifice and mercy/fellowship. As Beck points out in our Christian conversations liberals and conservatives tend toward one pole or another. Although he's not trying to make Jesus into a modern liberal Christian (Richard stands to my theological right), he notes that for Pharisees Jesus was a liberal who they believed disrespected the authority of tradition and law.
In sum, liberals will often find appeals to Purity/Sanctity illegitimate (or, more precisely, they will tend to privilege considerations of harm and justice). Conservatives will tend to give these appeals to Purity/Sanctity full consideration and weight and will, frequently, privilege them over appeals to harm and injustice. For example, compare how Jesus and the Pharisees appeal to the various moral foundations in Matthew 9. How do mercy and sacrifice align with the moral foundations? It seems clear, if we follow the voice of Hosea and the minor prophets, that mercy is aligned with the foundations of Harm/Care and Fairness/Reciprocity. By contrast, sacrifice is clearly an appeal to the foundation of Purity/Sanctity. Given this alignment it can be argued that Jesus is privileging one moral foundation over the other: “I desire mercy, not sacrifice.” In light of Haidt and Graham’s research, Jesus seems to place himself in the liberal position. No doubt this is exactly how the Pharisees experienced Jesus: as a religious liberal showing disrespect to authority and tradition and flaunting the purity codes by eating with “tax collectors and sinners.” [Richard Beck, Unclean: Meditations on Purity, Hospitality, and Mortality (p. 61). ]
We needn't always choose between purity and mercy. There would seem to be a place for limits on behavior. Surely even those of us on the left side of the center mark don't believe that anything goes? Paul can say, "all things are lawful, but not all things are beneficial." But where do we draw the lines and doesn't mercy ultimately trump purity?
One of the places where this becomes an issue is the church's table fellowship. Beck talks at length about the Lord's Table -- but as we consider the question of purity and mercy, following Jesus' own table fellowship, how open should the Table be?