Question

What was the idea of supreme god

Answer 1

For Vaishnavites, Lord Vishnu is God. For Smartas—who see all Deities as reflections of the One God—the choice of Deity is left to the devotee. Most Hindus, in their daily devotional practices,worship some form of a personal aspect of God, although they believe in the more abstract concept of a Supreme God as well.

Answer 2

The idea of supreme God is that there is only one God in this world and it can be attained or approached with devotion and bhakti.