Where in the Law is that? "it is unlawful for a Jewish man to keep company with or go to one of another nation", where is that in the Law? I think it's an oral law, or what today would be called a canon law, in the Catholic Church. But there's no Catholic canon law that says anything at all like that.
5 These twelve Jesus sent out, and commanded them, saying, “Do not go into the way of the Gentiles, and do not enter any city of the Samaritans. 6 But go rather to the lost sheep of the house of Israel. 7 As you go, preach, saying, ‘The kingdom of heaven is at hand.’
Or did you mean in the first 5 books? Because Paul did when he said God is taking down the wall. He put it up, he can take it down.
31 And I will set your bounds from the Red Sea to the sea, Philistia, and from the desert to the River. For I will deliver the inhabitants of the land into your hand, and you shall drive them out before you. 32 You shall make no covenant with them, nor with their gods. 33 They shall not dwell in your land, lest they make you sin against Me. For if you serve their gods, it will surely be a snare to you.”
In order to approach God, a person not under the covenant of circumcision must first bless Israel. Then enter the covenant. Now, we are saved by grace, to drive them to jealousy. Hopefully the jealousy part makes more sense now.
Did they have man made customs? Of course they did. Just like the Church of Rome. And he rebuked them for having their customs in place of his written laws.
5 Now therefore, if you will indeed obey My voice and keep My covenant, then you shall be a special treasure to Me above all people; for all the earth is Mine.
When the Lord your God brings you into the land which you go to possess, and has cast out many nations before you, the Hittites and the Girgashites and the Amorites and the Canaanites and the Perizzites and the Hivites and the Jebusites, seven nations greater and mightier than you, 2 and when the Lord your God delivers them over to you, you shall conquer them and utterly destroy them. You shall make no covenant with them nor show mercy to them. 3 Nor shall you make marriages with them. You shall not give your daughter to their son, nor take their daughter for your son. 4 For they will turn your sons away from following Me, to serve other gods; so the anger of the Lord will be aroused against you and destroy you suddenly. 5 But thus you shall deal with them: you shall destroy their altars, and break down their sacred pillars, and cut down their wooden images, and burn their carved images with fire.
6 “For you are a holy people to the Lord your God; the Lord your God has chosen you to be a people for Himself, a special treasure above all the peoples on the face of the earth.
THIS IS PETER'S CHRUCH. His church was set aside. If you read Acts 10 and 11, they were upset because they knew he ate with them and had the "forbidden fruit" of the gentiles, bacon. The Holy Bible disproves and contradicts the RCC first century letters of succession. They were made up. Peter's church has no succession, especially not gentiles.