The hypocrisy of the scribes and Pharisees, about whom Mark is less than fair as a matter of history, is a running theme of the gospel. In the passage read at mass today, Jesus takes on their criticism of his disciples for eating without washing first. It is not, says Jesus, what goes into someone which makes them unclean but what comes out of them (things like greed and malice).
Here is how I think a good proportion of modern readers understand this passage: what really matters is what’s inside us (i.e. in our thoughts, or our ‘soul’), the inner life, our intentions. Ritual and religious activity is an external matter, and not that important. Mark’s Jesus, on this reading, is a kind of proto-Protestant, suspicious of externals, as well as a kind of proto-Cartesian, since he thinks that we can draw a neat line between the inner and the outer, the ‘real me’ hidden deep inside and beyond all the bodily show.
But of course we can’t. We are animals, albeit animals of a certain sort (namely ones capable, at least sometimes, of being rational). It is precisely in our interaction with the material world of which we are part, whether that interaction takes place at the picket line, the soup kitchen, or the eucharistic altar, that our character is both formed and made manifest.
And nothing in this passage suggests otherwise; Mark can’t have been that bad a theologian. Apart from addressing a particular dispute, quite possibly a live one in the community within which Mark was writing, about food regulations – hence all the stuff about ‘what goes into a person’ (ἄνθρωπος), which we ought to read literally – the key point is summed up in the quotation from Isaiah:
This people honours me only with lip-service,while their hearts are far from me.The worship they offer me is worthless,the doctrines they teach are only human regulations.