When one thinks of God, one naturally thinks of limitless spirit, without
restrictions or parameters. Consequently, according to this line of
thinking, He must be formless. And in the Western religious tradition,
it is generally taught that God is, in fact, without form, or, that if He has any
form at all, it cannot be perceived by living beings. (See Exodus 24.10, Exodus
33.20, John 1.18).
In India, such ideas are often endorsed as well, as in, for instance, the Śvetāśvatara Upanishad (Adhyaya 4, Text 20): na saṃdṛśe tiṣṭhati rūpam asya na cakṣuṣā paśyati kaścanainam (“His form cannot be seen, for no one can perceive Him with
the naked eye”).