How to easily defeat any argument for God

[GrandizerII]

But slavery didn't benefit society considering that many people died in civil war and that society still looks down on black people resulting still in many inequalities, like black families being generally poorer than white families.

Long term benefits, and the comparison would
be would the lives of the descendants and future generation of blacks have been better in Africa. I’m not saying their  lives are better than an alternative in which slavery didn’t take place, but assuming these future generations our nation as whole was better in the long run, if more people benefitted for those 200 years of slavery, in the long run (ultimate increase in wellbeing) would it make it moral, or any less immoral? The point I’m making is that wellbeing, especially in the long term, doesn’t make things right and wrong.

It would have been wrong based on the treatment of blacks, regardless of the benefits it could offer society as a whole.

Hence why I don’t view well being as a good objective for morality. First and foremost because that’s not how morality works, and in most cases like slavery were just retro fitting well being after the fact, rather than any of us  objectively trying to analyze the long term
Benefits vs negative impacts, and deciding where on a moral judgement after doing so. We decided it was immoral regardless, of this.

This assumes that slavery could ever increase the wellbeing of slaveholders in such a significant way as to override the decrease in wellbeing of the slaves. Perhaps this may be so in fantasy scenarios, but I'm not convinced this has ever been the case in real life.

Also note that you have not yet given a rational basis as to why slavery would be wrong. If it's not to do with wellbeing, then what is it then?