Throughout history, people have sought to explain the reasons behind the myriad of Torah laws, especially the dietary laws. After all, it seems to make no sense why Jews can, for example, eat grasshoppers but not pigs. And so a raft of reasons have been proposed, from health arguments (trichinosis) to the assertion that because G-d desires blind obedience, he gives us rules that are not even supposed to make sense.
Also common is the suggestion from both Jews and Christians that the reasons for Jewish dietary laws are social: if, because of specific dietary restrictions, you do not break bread together, then you are not going to mingle, which means that intermarriage is less likely. This helps explain why Jews have managed to stay distinct, one way or another, for thousands of years without a homeland of our own. But such a approach is arguing from historical result, not from the text itself. In other words, while it is true that separation reduces intermarriage, the text itself does not say that this is why we have the dietary laws.
What the Torah does do is describe itself as a guide or recipe for positive relationships with G-d and with man. To that end, all of the laws in the Torah have symbolic meaning that we can and should use to inform our own lives, to help guide us toward holiness in all that we do. That includes dietary rules, which are not difficult to explain using the text itself. Here is my explanation, which has nothing whatsoever to do with health, blind obedience, and especially not for social separation from outsiders.
Indeed, the text gives us counterexamples, favorably telling us of “mixed” meals.
These counterexamples are in the text itself. The Torah tells us that Avraham loved having and serving guests, sitting with them while they ate:
Looking up, he saw three men standing near him. As soon as he saw them, he ran from the entrance of the tent to greet them and, bowing to the ground, he said, “My lords, if it please you, do not go on past your servant. Let a little water be brought; bathe your feet and recline under the tree. And let me fetch a morsel of bread that you may refresh yourselves; then go on—seeing that you have come your servant’s way.” They replied, “Do as you have said.” Abraham hastened into the tent to Sarah, and said, “Quick, three seahs of choice flour! Knead and make cakes!” Then Abraham ran to the herd, took a calf, tender and choice, and gave it to a servant-boy, who hastened to prepare it. He took curds and milk and the calf that had been prepared and set these before them; and he waited on them under the tree as they ate. (Gen. 18)
And later in the text:
Jethro, Moses’ father-in-law, brought a burnt offering and sacrifices for God; and Aaron came with all the elders of Israel to partake of the meal before God with Moses’ father-in-law. (Ex. 18:12)
In other words, breaking bread with a man who is elsewhere described as a priest for a pagan religion presents no problem at all – and everyone important comes to join in that meal!
There is an underlying facet of Judaism which can be seen both in the text of the Torah and in my contributions offered to the non-Jewish world on the internet: Judaism does not shy away from interactions with non-Jews. To be sure, we avoid assimilation risks, and we are strictly forbidden to engage in idol worship and pagan practices around us (within which I include Earth Worship in all its green forms). But Torah Judaism was never meant to be introverted; one cannot be a “Light Unto the Nations” if the light cannot be seen.
So, too, in the case of Jethro. He reunited Moses’ family, and then they caught up:
Moses then recounted to his father-in-law everything that the LORD had done to Pharaoh and to the Egyptians for Israel’s sake, all the hardships that had befallen them on the way, and how the LORD had delivered them. And Jethro rejoiced over all the kindness that the LORD had shown Israel when He delivered them from the Egyptians. ‘Blessed be the LORD,” Jethro said, “who delivered you from the Egyptians and from Pharaoh, and who delivered the people from under the hand of the Egyptians.’
Suitably impressed, Jethro brought an offering to G-d (as a pagan priest, he would have been comfortable with practicing polytheism), they all shared a meal, and he went back to his home.
There is a lesson in this for modern Jews as well as all people: we benefit from positive interactions with others. We know, of course, that those interactions are not necessarily positive: when Jacob separates from his father-in-law, Laban, it is a negative experience from beginning to end. They exchange accusations and threats, and separate with a “don’t cross this red line” kind of truce. That is the kind of interaction and blocked relationship we must always seek to avoid, whether with fathers-in-law or anyone else.
It is worth remembering that the Torah continually contrasts Israel and Egypt, because they are meant to be opposites in so very many ways. Egypt chose the opposite path with outsiders: the Torah tells us that the Egyptians would not share meals with Joseph or his brothers, because to eat with a non-Egyptian was taboo. There are consequences for this kind of mindset: cultures that refuse to meaningfully interact with outsiders, with those who think differently than they do, necessarily stagnate and fail from the inside out.