Huh, so it isn't an old throwback to the thinking that the Sky's above are heaven where G!d resides... ?
Well it's
way more universal than that. It's only a 'throwback' if the metaphorical significance is opaque. People speak of 'uplifting experiences' or being 'down in the dumps', for example. Water flows downhill. It's so common, it's so ubiquitous its almost invisible.
Svarga Loka are the eight planes of Hindu cosmology, the highest
Goloka is located on and above Mt. Meru. It is where the righteous live in a paradise before their next incarnation. Below the seven upper realms lie seven lower realms of
Patala, the underworlds. Greek mythology has Olympus and Hades, the examples are endless ...
A belief in the
axis mundi or world tree comes about because the tree transverses the horizontal plane. To the simple eye the roots are the mirror image of the branches, so we have a physical sign that lends itself to expressing the idea of the connection between this world and other worlds, located as higher or lower in reference to this one. The totem is derived from the tree. The world tree figures in nearly all Indo-European mythologies, as well as among the First Peoples of N & S Americas.
The idea of a paradisical state as above is common to the Abrahamics and the Ancient Near East, to Buddhists and Hindus. It's in Confucianism and in Chinese mythologies the Supreme Deity, Heaven and sky have a common root. Japan is the same, with deities both spiritual and human known as the Son of Heaven. It's there for Brahmins, Jains, Polynesians ...
It's everywhere, it's universal and it's a viable metaphor, whatever you choose to make of it. I really think your prejudice against its Abrahamic expression are getting in the way. It's a finger and the moon thing.
If simple people choose to image God this way, there's nothing wrong with that. It's no less accurate than any contemporary abstract intellectual concept, and often a lot more expressive and inclusive than the somewhat forensic expressions.
In
Inside the Neolithic Mind, the authors argue that the imagery are so similar across time and space that a neurological explanation might be at play, drawn from subjective perceptions of altered states of consciousness. The NDE of 'entering the light', for example. There are corollary distressing experiences which share some similarities with the concept of Hell (whether that's because of education, I'm not sure). The positive experiences of 'the light' as intense feelings of love, peace, joy, bliss, one-ness transcends the everyday world.