The main reason I'm an atheist

[Wryetui]

Now someone who actually answered! Thank you.

However, the size of the universe has nothing to do with the existence of God. And that is what the OP stated, that, as the universe is as big, it cannot the possible (somehow) that God exists. I have seen in this something incorrect and unrelated.

We could talk about how small humans are in relation to the universe and other things like that, but that would be just speculation since nowhere in the Sacred Scripture or the Sacred Tradition it is stated why the Creation is so vast (perhaps because such an information would be quite useless to the people living before Christ, for example), but however big or small is the universe, it has nothing to do with God's existence.

As I just said, the size of the universe can't prove the existence of gods one way or the other. HOWEVER, the vastness of the cosmos and humanity's seeming irrelevance within it does bring into question the idea that a god that has personal interest in human affairs exists.

That is, what we could call, speculation. No matter how big the universe is, I do not know if God has actually done something to that vast universe (I am talking about outside of the Milky Way), but I do know for sure that God has personal interest in human affairs, as you put it. That is proven by the fact that since the very human ever existing (Adam) God never stoped having a relationship with humanity, ultimately seeking to redeem it from the corruption and death that its ancestors (Adam and Eve) have put them to, by uniting the fallen human nature with the divine nature of Christ, God. If you do not believe that God is intimately united with every human person on earth and is present at every movement you make, or every thought you think, you are not talking about christianity, because this is exactly what christianity states.