India has its ethos rooted in a rather liberal idea of God. At the root of Hinduism is is an idea of a ‘Brahman’ which cannot be translated to God in English. The idea of Brahman is that of a certain ‘consciousness’ that pervades all that we see manifest in the Universe (and is the cause for all that exists).
With this idea it was easy for the Rg Vedic seers to proclaim — “Truth is ONE; Sages call ‘it’ by many names”. Said in other words, “just as all rivers lead to the ocean, all religions lead to the same Creator”.
“Ekam Sat Viprah Bahudha Vadanti”: Truth is one, sages call it by various names.
This is the central theme based on which has the entire foundation of the Indian civilization, it’s endless religions and sects, and it’s culture been built. This is a “core value” system that India espouses, which I believe most Indians across most religions, specifically those belonging to indic religions, still live by. This value system naturally leads to acceptance, and even respect for all faiths.
This core value manifests in all indic religions — Hinduism, Jainism, Buddhism (even with its atheistic overtones), Sikhism and the hundreds of sects within and outside mainstream Hinduism such as the Kabir-panthis. As Sufi-Islam came in touch with Hinduism there was complete acceptance of the populace of India, in accepting its saints and mystics as ‘Gurus’ bearing testimony to the same “core value”.
This is the thread that has weaved India into a spiritual, cultural and even a geographical ‘idea of India’ for over 5000 years.