The Old Testament is the Law, the New Testament is Grace.
So God changed His mind? That thing He wrote in stone? The one that said REMEMBER, we should now just forget? Why didn’t God get it right the first time? And what’s this with Jesus kept the Sabbath and He is our example but we should just follow what the RCC says instead?
Matt 5:17-19
Think NOT that I am come to destroy the law, or the prophets: I am come not to destroy but to fulfil. For verily I say unto you, Till heaven and earth pass, one jot or tittle shall in no wise pass from the law, till all be fulfilled. Whomsoever therefore shall break one of these least commandments, and shall teach men so, he shall be called least in the Kingdom of heaven; but whomsoever shall do and teach them, the same shall be called great in the Kingdom of God.