It appeared in religious literature many centuries ago, probably in Mesopotamia (we don't have written testimonies before them) to express god-man relation. Ma

It appeared in religious literature many centuries ago, probably in Mesopotamia (we don't have written testimonies before them) to express god-man relation. Many religions nowadays are still based on the concept of a master God and a slave human follower The Bible is the most simple example were slavery is accepted and considered normal (slaves, concubines, that became domesti workers but we're still slaves) Another example is God that asks Abraham to kill his child, and Abraham obeys, because he's an "humble servant" There are still many prayers that refer to God as The Lord (master) and the believers are servants to God (slaves to God, sometimes literally) * “Amen, amen, I say to you, no slave is greater than his master nor any messenger greater than the one who sent him.” * Said Jesus to his disciples in John 13:16 That's where it was born And that's why it stayed It really wasn't a joke, it was all very serious.