Upvote:2
Various solutions to this conundrum have been proposed; I'll share the 2 that I find require the fewest assumptions:
No man in his frail, fallen, imperfect state can stand in the presence of God. Those who have seen God (such as Abraham, Jacob, Moses, Isaiah, etc.) were transfigured so that they could temporarily withstand the glory of His presence.
Statements in John 1:18, John 6:46, and 1 John 4:12 use verbs ὁράω (horaó) & θεάομαι ("theaomai") for "to see" that can be used both in a literal sense (to physically see) and a metaphorical sense (to grasp a concept or deeply understand). Since John is clearly familiar with the Old Testament, and when he wants to emphasize that he physically saw something, he knows how to say so with no ambiguity whatsoever (see 1 John 1:1), it is both grammatically possible & contextually appropriate that John is saying nothing about physically seeing God. Rather, he's pointing out people's inability to fully perceive or understand God. "To see" can carry a similar metaphorical meaning in English, such as "I see your point."
My observation (sorry, pun intended) is that John is saying (to use a different play on words that would also confuse literalistic readers 2 millennia from now) that there is more to God than meets the eye.
Upvote:2
The clue is in the verse you quoted. "he hath declared him" Or 'made known'. There is ample evidence that 'seeing' does not mean with the eyes, but with the mind and heart - hence 'knowing God' is the emphasis here not a visual sighting.
No one knows the Son except the Father, and no one knows the Father except the Son and those to whom the Son chooses to reveal Him. matt 11:27
Here Jesus again amplifies the importance of 'knowing' the Father. He is the only one privy to this state (obviously, as that text is quite clear) of intimate understanding. He would share that with his brothers - he being the 'only way' to the Father.
While there are several occasions where men have claimed to 'see' God, they have always witnessed a manifestation of some kind as God is invisible!
The Son is the image of the invisible God Col 1:15
If you cannot see that which in unseeable, then what you do see must be something other. What is seen is NOT God Almighty the Creator, but a form or image of Him - a cloud, an angel, a man - in Paul's example, Jesus.