Learning through Experiences, Not through Revelations

We learn and modify our rules of living life according to our experiences. We did not change many ugly practices  of human society due to any divine revelations. Slavery is one of them.

Slavery is legal practice in all major religions. Its only prohibited by laws now, due to the raised consciousness of human societies. We learnt with the passage of time that slavery is inhuman practice.

Since slavery is permitted by Islamic law, Muslim countries have used secular law to ban it. Some countries outlawed slavery only comparatively recently:

Qatar in 1952
Yemen and Saudi Arabia in 1962
Mauritania in 1980