Humans were created with freewill in the likeness of God:
" Then God said: “Let us make man in our image, according to our likeness."-Genesis 1:26.
The fact that we are able to contemplate eternity, unlike unreasoning animals, shows us that God has put eternity into our hearts:
"He has made everything beautiful in its time. He has even put eternity in their heart."-Ecclesiastes 3:11.
We cannot see into the invisible realm where God resides and from whence the physical realm of existence came into being. But we can perceive it is there. The very fact that you are able to conceive of the notion of God is proof that he is real. Animals do not reason on god, they are not spiritual, they cannot peer into the unknown with their mind's eye, nor do they contemplate eternity. Things which we have been given. It takes a little contemplating to realize these simple truths. They are not complex or difficult to understand. That is why we are also told that to refuse to acknowledge a maker in the creation as we contemplate it is inexcusable in God's eyes. I imagine to him someone who ignores his existence is absurd. He is probably thinking, and rightly so, we should be thanking him for life and all that he has done for us:
"For his invisible qualities are clearly seen from the world’s creation onward, because they are perceived by the things made, even his eternal power and Godship, so that they are inexcusable."-Romans 1:20.
"You are worthy, Jehovah our God, to receive the glory and the honor and the power, because you created all things, and because of your will they came into existence and were created.”-Revelation 4:11.