I've asked you all kinds of questions as to what you think morality is. Very specfic questions, in fact. More than once. So don't even try it.
The Bible's "notions of morality and justice" are not entirely mine. I disagree with many of the Bible's moral pronouncements. Slavery being one of them.
Perhaps you could explain what is circular about it.
We're talking about well-being, remember. "Good" is something that contributes to human well-being. "Bad" is something that detracts from it. That value judgment is the subjective part. We are constrained by the physical rules of the physical world we live in. We cannot make decisions outside of those rules. There are a finite list of things we can decide upon, within the framework of those rules. That is the objective part. The decisions we make within those parameters can be viewed as objective.
I've heard this chess analogy before, maybe it will help. Within a game of chess, there are very specific and well-defined rules that you must follow if you want to play chess. Within those parameters, there are a number of different moves you can make while playing the game; some will be objectively "good" moves, and some will be objectively "bad" moves. Some "good" moves will be "gooder" than others and some bad moves could be "badder" than others. But whatever move you weigh out and decide to make, you're still constrained by the overall rules of the game.
It's simple, really, since I used to play chess competitively. Are you trying to win the game per the rules? Show off? Crush the opponent? Throw the game? Delay the game for a brilliancy you want to work toward?
You seem to think that good and bad are universals. They are not to all persons, all places and all times.
The circular reasoning of yours involved saying X is good and Y is bad, therefore the Bible has flawed morality. Your syllogism:
All slavery is bad.
The Bible advocates slavery.
The Bible is bad.
Other than the obvious fact that I believe the Bible teaches a feudal style of indentured servitude that is not Western slavery, invalidating and eroding your second premise, you have to defend why slavery is bad, why bad is a "thing", since "bad" is subjective and also a metaphysical concept. BE CONSISTENT. Explain how you believe "bad" is a metaphysical reality OR how slavery is "bad" or how "you know the rules of goodness and badness, and how they're obvious and universal, like some set of FIDE chess rules," or stop playing in the religionist's sandbox, where the syllogism is:
If objective moral values exist,then God exists.
Objective moral values exist.
Therefore,God exists.
Your very argument
against the scriptures, "their are clear moral lines the Bible transgresses," is a support of my syllogism that moral values underscore the divine reality.