For Crossan, one of the keys to understand Jesus is his practice of “open commensality” or open table fellowship; his willingness to share common table with all sorts of people: the sinners (those common folks with minimum acquaintance with the Law), the tax collectors, the Pharisees, etc. This practice ran counter against what good Israelites would do at that time, since basically they wouldn’t share table with those who were unclean ritually. In the beginning, the aim was simple and actually valid. Some three hundred years ago, the Greeks invaded the land and Hellenization was on its way. The Jews must be assimilated with the new culture (which involved bacons and pork knuckles, big no no to the Jews), and naturally they resisted. Not all, though. So eating became a highly symbolical and theologically-charged event. It shows where your allegiance is. If you want to stay true to YHWH, you will keep your ritual purity and hence you must eat with those who keep it as well so that you won’t be unclean. Separated tables with the unclean and the Gentiles became a new mark of identity of true Israelites.
So, when Jesus ate with the sinners and the tax collectors, the world turned upside down. He basically tore down the more commonly accepted social norm at that time (you can tell about social classes in our contemporary world from the practice of eating as well). He re-constituted Israel around himself. What counts as being Israel now is not to keep your ritual purity, but whether you are willing to eat with Jesus (since basically Jesus is willing to eat with everyone). The Pharisees understood this very well, and that’s why they were pretty upset about it (although some were willing to share the table with Jesus). They have been the guardian of the tradition, and suddenly this new chap came and subverted the honoured rule. They separated themselves from the sinners to guard the identity of true Israel; Jesus shared a table with others and re-defined Israel.
Hence, eating is not simply a mean to an end. It is not simply used by Jesus to teach and advance his mission (although he did teach when they ate together). Eating together by itself is an end. It symbolically shows that the foretold eschatological kingdom of YHWH has come. The prophets envisioned a time where people from the east and the west will come together and have a feast together in a banquet of YHWH. When Jesus shared a table with all kinds of folks, it indicated that, indeed, the time has come. Eating together is a performative mission practice.
In the same vein, when we eat with others, it is not simply an avenue where we can talk about the god whom we believe in. It actually speaks about what kind of god we believe in: are we willing to share our table with those whom we consider not worthy to share?
Feuerbach said that god is basically projection of our dreams and reflection of our perfect self wannabe. In other words, we tend to create god(s) in our own image. Similarly, Schweitzer criticized the historical Jesus projects in the 19th century as basically personal reflections of the scholars who pursued the historical quest. In the end, what we see is not Jesus, but simply our reflection in the mirror. I would say that open table fellowship is completely otherwise for me. I am thoroughly uncomfortable with this practice, since I tend to be very anti-social when I want to eat. I prefer to eat alone. There are just too many moments where I feel awkward for not knowing what to talk about with those who share the common table with me. Hence, this practice of Jesus keeps prodding and provoking me to counter my own self (although, it is equally valid to say that cognitive dissonance could be a powerful theological force as well), to realize that in the end life is not only about me, but to be shared with fellow pilgrims in the road to Emmaus. Hopefully, we will arrive and share a common meal together with the Lord at the very end of our journey.