The argument is not that we are 'under' the way and system of the law of Moses (but you keep hearing it that way). The argument is that we are 'under' the law of Moses in this sense:
"31 Do we, then, nullify the law by this faith? Not at all! Rather, we uphold the law." (Romans 3:31 NIV)
This is your chapter and verse. Do you disagree with Paul? Yes, or no?
You have said this verse is only speaking to Jews, but you time and time again refuse to answer my question as to why Jews who have faith in Christ are still 'under' the law, but gentiles who have faith are not 'under' the law.
I'm pretty sure you have to be 'under' something to uphold it. So explain how believing Jews do that, and then explain--if I understand you correctly--that believing gentiles do not do that.
And here's my question again for you to answer so we can put this discussion to rest:
When Paul said "we uphold the law (by faith)" did he mean that faith keeps the literal Sabbath, and that anyone who does work on that day must be literally put to death?
Yes, or no?
If you answer 'yes', then you contradict your own doctrine that says we are not 'under' the law of Moses anymore (as you have been stressing what 'under the law' means), so you're probably not going to answer 'yes'. But if you say 'no' then you have to explain how faith upholds the law of Moses.
Simple, yes or no question. Here's your chance to clear things up once and for all.