If Vaishnavism is so popular and wide spread in India, the credit must go to Sri Ramanuja, who took advantage of the ecstatic outpouring of the south Indian mystics, the Alvars, and produced a highly logical philosophy of knowledge soaked in devotion as the easiest means of God-realization.
What is material and what is not material? When the world is the end and God the means to attain that end, then that is material. When God is the end and the world is only the means to attain that end, spirituality has begun.
-Swami Vivekananda