How can slavery coincide with the Golden Rule within Islam?
I guess about the same way the Golden Rule coincided with slavery in Buddhism, Hinduism, Christianity and Judaism for all of human history till the last two hundred years or so.
It is also a fact that orthodox Judaism prescribes very different standards of conduct from one Jew to another as compared to gentiles. Christianity is unusual in that its moral prescriptions are more or less universal.
Other religions have evolved AWAY from the concept of one man being the possession of another. The ideology of Islam, however, is that the slavery is an integral part of their Shar’ia law code, the “them” in the “us versus them”. Slavery is prescribed as the means by which the elitist few, the Noble Islamic Gentlemen, may maintain and extend their despotic rule, over all the lesser people and the entire female gender.
There is no equality of men and women under Shar’ia law, and very little affirmation of any degree of humanity extended.
But then, life is uncertain.