Full disclosure I am not Jewish. This is (it sadly needs to be said) not meant to be anti-Semitic in any way, shape or form, but it's an honest question. I am not that familiar with the Talmud or oral law but I am pretty familiar with the Hebrew bible and am learning more every day.
In Deuteronomy 4:1-2, in the English Standard Version, it is written:
And now, O Israel, listen to the statutes and the rules that I am teaching you, and do them, that you may live, and go in and take possession of the land that the LORD, the God of your fathers, is giving you. You shall not add to the word that I command you, nor take from it, that you may keep the commandments of the LORD your God that I command you.
I think the difference between Bris Milah and Bris Periah is commonly understood in Judaism and the view that Periah was added centuries later - not until the age of the Greeks and Romans- is not challenged. If I'm wrong, feel free to discuss, but consider consider Exodus 4:25 "Then Zipporah took a flint and cut off her son’s foreskin" ( i.e. just like that)
I'm wondering [in an 'ask a Rabbi' fashion or something], learning as I have about the difference between Bris Milah Versus Bris Periah, how does Deuteronomy 4 and the prohibition against adding to the commands of God not apply here? It seems like a substantial addition to a commandment.
That's my sole question and I don't want us to venture outside the narrow scope of the above, but if you're curious about my interest as a non-Jew, I consider myself to (very personally and inseverably) have skin in the game, precisely because I no longer have 'skin' in the game, otherwise I probably wouldn't even know what these things are.
Thank you, Shalom and Simcha
Edit: It seems that people use Joshua 5:2 as evidence that Periah was always a thing because of the command to circumcise the Israelites again before entering the promised land. I do not believe a plain reading of the text justifies this, if you read through to verse 8.
4Now this is why he did so: All those who came out of Egypt—all the men of military age—died in the wilderness on the way after leaving Egypt. 5All the people that came out had been circumcised, but all the people born in the wilderness during the journey from Egypt had not. 6The Israelites had moved about in the wilderness forty years until all the men who were of military age when they left Egypt had died, since they had not obeyed the Lord. For the Lord had sworn to them that they would not see the land he had solemnly promised their ancestors to give us, a land flowing with milk and honey. 7So he raised up their sons in their place, and these were the ones Joshua circumcised. They were still uncircumcised because they had not been circumcised on the way (NIV)
I don't mean to be controversial but I don't know how it could be written more plainly in my translation.