You seem to have no idea who is saying the things you are saying.
You simply have no idea what the word subjective means. And you continue to refuse to actually address the multiple proofs I've laid out for you. It's typically taken as a sign of weakness of argument if in response the other debater cannot produce a full response to the offered proof or argument. You never do. All you do is keep repeating that if it's man that says "there is no highest moral instance" than man is "the highest moral instance". You've yet to even offer an argument as to why that makes any sense. (Which is not surprising, as it makes no sense whatsoever.)
Let me offer you an analogy. You may well believe their are unicorns (you seem to believe enough other crazy nutcase things), but for the sake of this analogy Premise 1 is that there are no such things as unicorns.
Premise (1) There is no such thing as a unicorns.
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Conclusion (1) There is no such thing as "the most X unicorn".
-> This is clear because as there are no unicorns, there cannot be one unicorn that is more X than any other unicorn.
Conclusion (2) There is no such thing as "the most beautiful unicorn".
-> This is clear from Conclusion (1).
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Are you starting to understand yet? If not, I'll make it even more clear. I'll show you how the argument about unicorns is exactly the same as that about morality.
Premise (1) There is no such thing as "good" or "bad"
-> This is the meaning of "subjective". If you're still confused about this word - and it seems like you are - you ought to buy a good dictionary. Perhaps English isn't your first language. If that's the case I apologize for seeming demeaning.
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Conclusion (1) There is no such thing as "the most X good" or "the most X bad".
-> This is clear because as there is no "good" or "bad", there cannot be one "good" or "bad" that is more X than any other "good" or "bad".
Conclusion (2) There is no such thing as "the most good good".
-> This is clear from Conclusion (1). We simply substitute "X" for "good".
Conclusion (3) There is no such thing as "the highest good".
-> This is clear from Conclusion (1) and is essentially the exact same as Conclusion (2), however in English we do not usually say "most good good" because it sounds awkward, so we choose other words. This is not true in all languages. In Chinese, for example, "the most good good" is a perfectly valid construction.
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If you still don't understand, then I suggest you really ought to learn the word 'subjective'. It's exact meaning is that there is no objective better or worse. It should be blindingly clear to anyone older than 12 that this implies that there is no objective "highest"/"greatest"/"worst"/etc. In fact, it's not even an implication. It is exactly what the word 'subjective' means. You're really just having a hard time understanding this word.
This isn't even a philosophical or logical argument. This is just you not understanding vocabulary.