Hmm, yes a cheeseburger is Rabbinical ( as well we are talking two different kinds of cows already

) Thank you L-rd! ( I love cheeseburgers) Now though as far as the communion; when it is taken so far that it is worshipped and held above all in a ( sorry I gotta say this) pagan manner of injesting the g-d then I have to say it is more than cultural, it is dangerous and not what Yeshua taught. This is not cultural, but a mixing of cultures, of Judaism into the Pagan religions of the time, and is a well documented fact. The L-rd was very strick in the Torah about mixing two of a different kind, and I believe this is part of it. The seed of G-d should not be mixed with the seed of the serpent, there is much danger in this.
Now I am not saying this because I want to put up a wall, because I believe that there are many in the churches that don't know any better, they are not Bereans, Sh'aul exhorted those who truly want to follow the L-rd G-d of Israel to test
everything! against what he said in his word, including I believe all that Paul told them. this was to learn , but there are many that either blindly follow what the priest or pastor or whoever is over them preach and not check for themselves or they just don't care. There needs to be a whinnowing out of the tares from the wheat, and people can do this themselves. To learn wht is tov and what is not.
But to assume that only jewish sages heard from God is meshugganah
No, I don't believe that only the Jewish men heard from HaShem, but that doesn't mean that everything that the Founding father heard was from him either. Such as the L-rds feasts and foods and Sabbath were from the devil. No, I don't believe that was a word from above.