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.
Those who work at a thing heart and soul not only achieve success in it but through their absorption in that they also realize the supreme truth -- Brahman. Those who work at a thing with their whole heart receive help from God.
-Swami Vivekananda