Question: God as One's Guru?
Do scriptures permit having God as one's guru?
Answer: Yes, Both Internally and Externally.
We must accept Krishna or God as our guru because He is the supreme authority. He orders us in the Bhagavad-gita to surrender to Him. He is manifested within our hearts as the caitya guru, the guru within. And when He brings us into contact with His external manifestation, the guru without, He orders to also surrender to that guru, the bona fide spiritual master. So if we decide that we will only surrender to the guru within and not the guru without, we are guilty of the logical flaw known as ardha-kukuṭi-nyāya, half-hen logic.
The farmer had a hen who laid very nice eggs. But he was unhappy that the hen ate a lot of feed. So one day he got a so-called bright idea. He decided the cut off the end of the hen that he did not like (the head) and only keep the end he liked (the rear end). He was so dull that after cutting out the hen's head he could not figure out why the hen stopped laying eggs.
So if we accept the guru within, while neglecting the guru without, we will find ourselves with a hen that does not lay eggs. In other words we will find that we are without any access to that wondrous spiritual sky. Therefore let us not be half-hen logicians. Let us intelligently both the guru within and the guru without, the internal guru and the external guru.