I can refer you to a Book written by Dr. Sangat Singh The Sikhs in History
which has very good detail about this concept.
Publishers Uncommon Book New delhi.
Nirmale Saints who were sent by Guru Gobind Singh Ji to Benaras for learning Sanskrit follow the Sanatan Sikh so are Nanak Sar and Other saints. Sanatan means inclusive. Guru Nanak's Message is afor all and it is above religious order for entire humanity, Basically Sri Guru nanak preached that no one is judged by the rligion he/she practices but by his/her good Deeds. I was posted in Us and was some times had to share my office with a Muslim who did not know much about Sikhism and was interested who can be a Sikh. So I asked him
Do you believe in Remembering Allahs Name all the Time in your Heart ? he said Yes
Do you belive that we should earn our living by hard work honesty and creativity? he said Yes
Do you belive that we should share our earnings with those who are less fortunates or needy - Charity? He said Yes.
So I asked him would you prey for welfare of all humanity and he said yes.
To this point I told him that you are already a Sikh.
This much is required to be a Sikh rest are to follow. he was very upset to be declared as a Sikh but I did not do any thing to be that way. I just identified him by getting to know his answer to my questions.
Sanatan Sikhs is inclusive.
Many Muslim and Brahmin Followers of Guru sahibs were sikhs in that way.
Regards
HP Luthera
