He is the visible manifestation of the eternal God. He is no imposter or deceiver. Jesus Christ is the God of truth. Jesus Christ is the true God. We can illustrate that from the human realm also.
Some people are mechanically inclined and enjoy building things.
I have a friend who likes to restore antique cars. He tears them apart and puts them back together again. He knows them inside and out, right down to the last nut and bolt. People are normally familiar with the things they build. Since He obviously knows all there is to know about everything He made, we are driven to the inescapable conclusion that He has complete and accurate information about everything there is.