you are right but there is some delicate point. There are many things which are not visible because they are cognate with us; they are not same substance as we are like the electricity in the cables, electromagnetic power, ... but we recognize their trace of existance from the impressions they have, and we may use them through devices & instruments.
God is not a substance so that we can see him, but He is a verity of Power, Knowlwdge, existance and whatsoever of the excellency is a trace of Him. That's why He said : "I was a secret Treasure, and liked to be known; then I created ( the human)."
It's very easy to open our hear t to Him and ask him to introduce Himself to us and guide us to know Him.
Not meaning to try to define or describe him by our imaginations which will be consequently of course the product of our thoughts and imaginations that is not the real God.