There is no spiritual basis for the caste system. Just as men and women are equal in terms of their spiritual potential, so too are all people. The Way Back do not recognise any caste system as a barrier to people benefiting from their teachings or practice.
Furthermore spiritual truth, by its very nature, must be true for everyone, since everyone comes from the same source. Just as the sun shines upon each person equally, and the wind blows against each person equally, then the spiritual light provides the same potential to each person equally.
The only limits a caste system presents to an individuals spiritual journey is how much they cling to it. Those who are loving in nature would not recognise caste in another person and would only see someone to love. It is the people who are loving who progress with ease on a spiritual journey. Those who have hate or judgement for others, who see another person as lower caste and do not respect them for it, will struggle on a spiritual journey because it is a journey to discover love.
How can any person profess to wish to attain enlightenment, which is to aspire to be one-thing-everywhere and the source of everything, and at the same time, reject or dislike other people? They would be rejecting and disliking a part of themselves. There is no place for caste in the seeking of TRUTH. Your caste does not determine your future, your heart does.