Nobody has ever seen God; the only begotten Son who is in the bosom of the Father, He has made Him known. John 1:18.

In the same gospel,

You have never heard the Father's voice nor seen His shape. John 5:37.

In Matthew,

No one knows the Father except the Son, and he to whom the Son wishes to reveal Him. Matt 11:27.

And in John,

I am the way, the truth, and the life. No one comes to the Father except through Me. John 14:6.

The truth that nobody can be joined to God except within the Lord is again the Lord's own teaching in John,

As the branch cannot bear fruit by itself unless it abides in the vine, neither can you unless you abide in Me. For apart from Me you cannot do anything. John 15:4,5.

The reason why nobody can be joined to God except within the Lord is that the Father is within Him and They are one, as is yet again the Lord's own teaching in John,

He who has seen Me has seen Him who sent Me, ... and you know My Father, and from now on you know Him. He who has seen Me has seen the Father. Philip, do you not believe that I am in the Father and the Father is in Me? Believe Me that I am in the Father and the Father is in Me. John 12:45; 14:7,9-11.

And in the same gospel,

I and the Father are one. ... [that] you may know and believe that the Father is in Me and I am in the Father^a. John 10:30,38.

Notes