Panentheism or the philosophy that self and cosmos are in God or localized parts of God may seem, at first glance, unproblematic. It may appear to have a ‘high’ view of God since self (and cosmos) are smaller and fragmentary in comparison to the infinite whole God. As such, the self (and cosmos) can be divine in one essential sense while ‘lower’ and ‘smaller’ and ‘partial’ in another sense compared to God. But this is precisely where the problem lies, which is at least twofold.
First, if the self or cosmos is essentially divine given it is a localized portion of God who is infinite in knowledge (omniscient), power (omnipotent), and goodness/love (omnibenevolent), then this implies that the self/cosmos is also omniscient, omnipotent, and omnibenevolent. For any portion of infinity is mathematically speaking infinity. Take a minute part out of infinity and that part is infinity while what remains is still infinity. Such is the mathematics of infinity. Thus, we would be forced to assert the infinite knowledge, power, and goodness of each human self. This is not substantiated by evidence of experience (mystical experience included) or observation or inference. It is a fallacy.
As far as we know, the universe does not appear to be imbued with any personal qualities of knowledge, potency, and love. Galaxies and stars and planets, subatomic particles and strings, quarks and quasars, black holes and dark matter, and any number of phenomena we seemingly observe, even the consciousness that knows the universe — none of these possess the omniscience, omnipotence, and omnibenevolence so central to the being and becoming of God.
Second, to assert that self or cosmos is a part of God is to assert that God has parts. That is, God is a compounded being. A compounded being is necessarily open to uncompounding or disintegration. This means God is not permanent and thus is not unconditioned but rather conditioned through and through. When causes and conditions holding God’s integrity are present, well and good. When absent, God falls apart. Thus, the unborn eternality of God is thrown into question—as a compounded entity, God is thus as contingent as everything in creation, powerless to stop its own disintegration. One may call this entity God but it is definitely not as omnipotent as we might think. The creator ends up being ontologically identical to the created. This logic applies to the self and mutatis mutandis to the cosmos.
For God to be truly God, pantheism and panentheism fail the litmus test.