Well lets see...
In Christianity, it is written that "no man has seen nor can see" (1 Tim. 6:15-16) and Jesus says "the kingdom of God comes not by observation, for behold the kingdom of God is within you" (Luke XVII.20-21), however there is a trinity, the Son and Father may be visible, but not the Holy Spirit
In Islam, "No vision can grasp Him, But His grasp is over all vision; He is above all comprehension, Yet is acquainted with all things" (Qur'an 6.103).
In Hinduism, the Upashinads, SB, and Bhagavad Gita state that God is the unchanging, eternal witness or observer existing before the material world, after, and in between just the same, beyond the senses, causeless, absolute bliss, reality itself, however God can show himself in physical form, although this physical form is not really God