You wrote: “Another way of looking at this is that the Messenger did not call people to prayers as it is not in the Quran and so the idea is false that it was done correctly and did not need ‘correcting’.”
This premise “…messenger did not call people….” is DEAD ON ARRIVAL, thus, the conclusions too. It is equivalent to accusing prophet of neglecting God’s explicit instructions. Prophet fully implemented this call to prayer and Quran is witness to this:
[5:58]: And when you call to prayer, they take it in ridicule and amusement. That is because they are a people who do not use reason.
You wrote: “The Quran explicitly states that we are to judge what people are doing by what the Quran says, we cannot do or continue something because it is not stopped/mentioned in the Quran!” Then you cited 10:37.
LoL!!! Where are the explicit words/phrases “we are to judge what people are doing by what the Quran says” in verse 10:37?
You wrote: “You cannot confirm the truth of previous scriptures by remaining silent on a subject and leaving it to personal of ancestral opinion that a thing is a religious obligation and must be done or else we are denying the Quran!”
I did not bring any previous scriptures in my discussion? Circumcision was brought up by you, not me. What I am simply stating is that Quran either prohibits something or makes something lawful or provides a punishment for some transgression. If you prohibit (or vise versa) what is not explicitly prohibited by God, you are denying the Quran, see below. If you neglect the law given in the Quran and follow another law for a specific transgression, you are denying the Quran. Those who do follow certain practices considering these to be Ibrahimic practices not otherwise covered in Quran have a powerful argument on their side as per Quran, whereas you have none except conjecture.
You wrote: “You cannot forbid what is not forbidden and BY IMPLICATION you cannot make lawful/a religious rite anything not mentioned in the Quran. You want to chop a bit off your anatomy, do so, but it is not sanctioned by Allah.”
Making something permissible (Halal, lawful/permissible) and prohibited (Haram/unlawful) is the sole prerogative of God. God has severely warned those who indulge in such activities in violation of the book. You cannot forbid what is not forbidden in the Book. Period.
[16:116]: And do not say about what your tongues assert of untruth, "This is lawful (Halal) and this is unlawful (Haram)," to invent falsehood about Allah. Indeed, those who invent falsehood about Allah will not succeed.
Where is the prohibition related to circumcision that you want to prohibit? None whatsoever. Since this was the Ibrahimic practice in vogue at the time of the prophet, God could have prohibited it if He desired so as He highlighted many transgressions of both polytheists and the people of the book. Yet, he did not do it, clearly sanctioning it implicitly.