It is not obvious at all. (And, a little tip regarding discussion and debate: The use of words such "obvious" and "clearly" not only offensively suggests that people who see things otherwise are stupid, but it often betrays the lack of a better argument that needs no such embellishing hyperbole.)
When the Pharisees that had come to Christ were telling the Gentiles they must be circumcised, isn't it obvious they believed that? Believe me, I personally do not mind you keeping the Sabbath, or even Sunday observers calling Sunday the Sabbath. To not do so would be a sin to either group, because we cannot go against our conscience. What is not of faith, is sin. I don't do either. My "observance" is every moment of every day.
But I do have a law within me I was taught as a child in the SDA Sabbath School, that is now a part of me. (I was recently talking to two other adult SDA's - one of them ex-SDA, that cannot break this "commandment" they were taught either.)
Nothing can be put on top of a Bible except another Bible. So in church, I just can't stand it when I see others putting their bulletin, glasses, or keys on top of their Bible. To me, and my friends, it shows a lack of respect for the Word of God. It is very distracting.
I'm sure you are the same about your own pet commandment that is part of you - the Sabbath. You can't stand it when others do not keep it, just as I am about respecting the physical book called the Bible.
All I'm saying is I understand, and would not try to change your mind, just defending myself against your judgment of me and others, as I try not to judge those who have not been taught my pet commandment, and unknowingly trespass against it. I also know that I must immediately forgive them, so that the Father will forgive my own unknown trespasses that irk others against me.
Christ Himself taught the disciples night and day. Yet he was constantly compelled to rebuke them for their lack of faith and slowness to believe what he had taught them. And even after they received the outpouring of the Spirit at Pentecost, both Paul and Christ had to correct Peter. People return to their old, defective habits and patterns of thought all too often. There is no reason to assume the apostles had not taught the converted Jews correctly. I have heard good sermons that didn't make sense to me until years later.
When did Christ rebuke Peter after receiving the Spirit? As for Paul and Peter, I tend to hold Paul more at fault, as we see only respect from Peter written about Paul. And Peter didn't do anything that Paul didn't do himself.
1 Corinthians 9:
19 For though I am free from all
men, I have made myself a servant to all, that I might win the more; 20 and to the Jews I became as a Jew, that I might win Jews; to those
who are under the law, as under the law, that I might win those
who are under the law; 21 to those
who are without law, as without law (not being without law toward God, but under law toward Christ), that I might win those
who are without law; 22 to the weak I became as weak, that I might win the weak. I have become all things to all
men, that I might by all means save some. 23 Now this I do for the gospel’s sake, that I may be partaker of it with
you.