No one can be 100 percent certain of these things. But the lack of evidence leads me to to the conclusion that god doesn't exist.
Maybe the reason you believe God isn't real is because you hold to a preconceived idea as to what God "is". And that arrived at by exposure to religions that describe "him" just so.
The Bible tells us that God is a spirit not a man. That we as men and women are created in the image and likeness of that spirit.
When God is eternal that would mean our flesh that is not falls away after death and what is left is that image and likeness, that spirit, that is God. All things that exist, if created by a spirit source must contain the attributes afforded its image and likeness as appointed by that spirit source.
God is all things. Including you.
Don't think the God of religion is the God that is easily rejected and therefore does not exist. Look in the mirror and see God there. Look at those you love and see God there. Look at those things in nature and see God there.
As long as you are conscious God is there. And when you are no longer so you return to the source that is the God that is everywhere.
Religion is human's feeble attempt to mold eternity into a box they can grasp hold of and understand using their limited consciousness that is molded to the experiences of this world. Consciousness that is formed from the time someone, anyone, tells us what this life is all about and what we can and cannot do, what can be and cannot be, within it.
Little one's who have invisible angel friends are a prime example of this. A child is the closest thing to God from the moment they are born. They arrive here born from the source of all that creates and they are still linked as if they have that invisible umbilicus attached to the Father (That pronoun is simply another label we apply. Spirit is genderless). That child who see's things that we cannot does see God.
That we do not means nothing. The scales over our eyes, recall Paul's affliction after meeting Jesus on the road to Damascus, shut us off from seeing the spirit in this world so that all we see is the illusion of matter in this world.
But that child knows from whence they came because they haven't yet been told to believe what this world expects of them.
You don't have to believe in man's idea of "God". Look in the mirror and know that eternal omnipresent spirit believes in you.
And "You" are only temporary.