This person certainly does not know anything about India. Can he explain why 7 million Muslims left India for Pakistan (there was a similar transfer of 7 million Hindus from Pakistan to India) but 36 million chose to remain in India? And why their population has increased to 180 million today. Is it that when there is persecution, the population of Muslims increases so dramatically, 5 times in 68 years, a 400% increase?
India did not go to Kashmir uninvited. It was the Pakistani attack and their atrocities which forced the Valley Kashmiris to ask for Indian help. Their leader, Sheikh Abdullah, asked for some safeguards and we agreed to them. Indian army did not move in till the letter of accession was signed. And what resistance he is talking about? Asking the 180 million Muslims to take up arms against 1000 million Hindus? Clearly, Servant is not in his proper senses.
As for OP's questions, I do not visit Christianity and Islam forums on principle. I do not know of an Indian Muslim to be a member of RF when I visit Comparative Religions or General Religious Debates forums. I do not like exclusivist religions, since my own view, 'Advaita', is all inclusive. Furthermore, I am a science person and find Christianity and Islam to be totally unscientific.
Of course, co-existence is possible and exists. Muslims were in Kerala since the 7th Century and were accepted in the society (they were known as sons-in-laws, Moplah, since some women in the matriarchal Kerala society of that time, married Muslims). Even after the Muslim invaders came at the turn of the last millennium, Hindus and Muslims have lived together, shared their happiness and sorrows, served their masters (whether Hindus or Muslim) loyally. Muslims are a part of Indian Army, Para-military forces and police. There is always a temple, a mosque and a church in every cantonment of Indian Armed Forces.
Hindus and Muslims do marry but not commonly, and yes, their marriage is not looked upon very favorably in general. Many Hindus have no problem with visiting the graves of Sufi saints. At one time people celebrated each other's festivals (Holi, Diwali, Eid) with enthusiasm which is somewhat lacking today - but, Hey, all is not lost.
Muslim children dressed as Radha and Krishna, Hindus and Muslims exchanging bread during the ‘Rottela Panduga’ at Bara Shahid Dargah in Nellore.
"Rotella Panduga" begins at Nellore Tank, Andhra Pradesh.