Similarly as we do not see God so many of us do not believe in Him. But just like invisible rays travelling to your mobile, FM radio, TV etc. God too exist in the Invisible form & is sitting silently within this infinite space watching all of our actions. Now if you have faith in this then you shall believe in God, otherwise not. As a matter of fact, God exists if you have Faith in Him, otherwise not. 'Faith" in God is prime to know about His existence.
Now if you do not have faith in God, then shall God cease to exist? God is truth & truth is always having existence. God was there when we all were not, God is there when we are having our present existence & God shall be there even when we shall not be there. He is the ultimate truth & truth exists always. In the night you see many stars in the sky but when the sun rises in the morning you do not see these stars at all. Now can you say that there is no existence of stars, as these shall be again visible, once the night comes & whole sky shall again lit with stars proving their existence. Similarly when our mind wanders in ignorance, during that time we do not believe in His existence but when our mind is lit with the light of knowledge, we are able to see the existence of God. Then we do not say that there is no existence of God.
God is the faith of human beings that a Supernatural Power exists in this universe which has created us & this all other universal forms. He is having supernatural powers, who is omniscient (knows everything), who is omnipresent (who is present everywhere), omnipotent (who is having all the powers & is all powerful), who is imperishable & indestructible. Faith of humans in such a big & great entity having all the powers is known as God.
In Bhagwat Gita God Himself is saying:
"yac chapi sarva-bhutanam
bijam tad aham arjuna
na tad asti vina yat syan
maya bhutam characharam" (Bhagwat Gita: Chapter Ten verse 39)
"Sri Krishna said: O Arjuna, I am the generating seed of all existences. There is no being—moving or nonmoving—that can exist without Me
"shraddhaval labhate jnanam
jnanam labdhva param shantim
acirenadhigacchati" (Bhagwat Gita: Chapter Four verse 39)
"Sri Krishna said : O Arjuna, a faithful man who is dedicated to transcendental knowledge and who subdues his senses is eligible to achieve such knowledge, and having achieved it he quickly attains the God & spiritual peace."
So just come out of the darkness of ignorance & have faith in God. It's the Faith in God only which shall deliver us from all the miseries of life. If you have Faith in God then it shall enlighten your thinking & let you come closer to all humanity & to God. Once you feel yourself one with all the humanity then peace, joy, bliss shall come to your mind as you shall see the image of God & image of yourself in all human beings.
Jai Sri Krishna