Question About The Unknowability Of Deity's Existence

I suppose that a belief that Deity cannot be known is older than Christianity (to which I adhere).  My own faith requires that I avoid disrespecting the faith, or lack of faith, to which others adhere.  But I do have a question.

     If Deity is unknowable (and, again, as a Christian I cannot assert this), what is the moral system (and what is its authority) is followed by those who adhere to that unknowability?

     Specifically, if one believe that God is unknowable in this life---and, if unknowable, this must also apply to God's Will (for knowing God's Will would be some proof of the existence of God)---how can such a person determine who, and who not, a human being may love?  By what scale of measure, and with that authority, is that assertion determined?

      If God is unknowable, and it follows that God's will is unknowable, than a moral judgement asserted must be mere individual opinion only, without authority to determine what is actually right or wrong; one can only determine what one thinks is unknowable.  Therefore, if Deity is unknowable, does it not follow that no one can assert any moral authority, only moral opinion?  In the sense of unknowability, how can an individual opinion claim any moral weight.  Or claim to speak for this unknowable Deity, or to speak to or for most of us.

      

       Would someone please help me figure this out?  

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