Here's the point. If you have a proper of understanding of how God relates to existence doubting the existence of God is ruled out. Simply put, atheism is impossible. You cannot doubt the existence of God.
There is a crude form of atheism. A simplistic version. This version of atheism assumes that God is some object in the universe like Odin, a giant teapot, or a flying spaghetti monster. In these versions of atheism, God is assumed to be some piece of furniture in the warehouse of the cosmos. A being among beings, a noun among nouns, an object among objects. And this version of atheism denies the existence of that object, that being, that noun. That if you searched the universe God will not be found. Therefore, God doesn't exist. And this is true. Christians agree with atheists on this point.
However, as I pointed out in my prior post, this vision of God's relation to existence is a confusion. God doesn't exist as objects exist. God is what gives objects their existence. Therefore, God cannot be located as piece of furniture in the warehouse of existence. God is the Existence which causes existence, the Being of beings.
When it is properly understood that God is the Source of existence, Being Itself, then it should be obvious why atheism is impossible. The human mind perpetually stands at the threshold of this mystery and is forced to ponder the Origin and Source of existence. God, properly understood, points to this Mystery.
Atheism is impossible because it denies the existence of an object and thereby demonstrates its metaphysical ineptitude. The Mystery of Being persists, obvious to any child, irrespective of any odd claim about what you might "believe" or "don't believe." The declaration that "God doesn't exist" is nonsensical.
Like I said, atheism is impossible.