Immortal doesn't mean omniscient or anything.
Such a view is essential to any theistic view of the universe which postulates God as the Creator, omniscient and all-good.
Buddhism repudiated the authority of the Veda, but found it needful to supply its place; and the word of the omniscient Teacher, faithfully reported by his disciples and guaranteed by concurrent traditions, became the rule of belief for the new Order.
The Parsis adore fire as the visible expression of Ahura-Mazda, the eternal principle of light and righteousness; the Brahmans worship it as divine and omniscient.'
The omniscient God, by means of His "scientia media" (the phrase is Molina's invention, though the idea is also to be found in his older contemporary Fonseca), or power of knowing future contingent events, foresees how we shall employ our own free-will and treat His proffered grace, and upon this foreknowledge He can found His predestinating decrees.
God is " all truth, all knowledge, all bliss, boundless, almighty, just, merciful, unbegotten, without a beginning, incomparable, the support and Lord of all, all-pervading, omniscient, imperishable, immortal, eternal, holy, and the cause of the universe; worship is due to him alone.