"Does that mean that it has no Religious roots whatsoever?"

The relgious connection is Varna- the division of work in society. All societies naturally stratify according to function, inorder to be able to function.

The Bhagavad Gita indicates the four main divisions of society , stating that a person acts according to his/ her nature (conciousness). There is no mention here that it locked by birth , just a person nature.

Indeed it is easy to see how as society declins (as predicted in Veda)those in power become corrupted and this can lead to opression.

Caste is a portuguese word and sdoes not properley explain the concept of varna.

Caste is very corrupt and while one may acknowledge the fact that every one is at different stages of their spiritual journey, that society stratifies, caste distinction should be done away with. Who can say who is realy a brahmin or a sudra in kali yug?