By this logic, same applies to God, if you can't explain God's existence it doesn't exist. There is also a serious glitch here. We can physically prove world's existence but not God's existence. We can easily claim that Santa Claus with natural powers created Universe for purpose of making people happy. We are in no position to prove or disprove that claim. In this case let's stick to what we can measure.
The first question you have to ask yourself is : "am I Insane or not?" or "Am I someone reasonable or not? If your answer is Yes I am Insane the World is inexplainable completly , then you are right God existence is useless.
But since you say the world exist and is Reasonable then automaticaly God existence must logicaly be.
Then if you say I can't explain God it 's equivalent to say that the World is not logical or insane for me.
It 's like Maths. I give you an example, We suppose Math is obviously logical and Right and not Insane.
Then Let's take the real interval [0 1], this interval exist then there exist a smaller ones include in [0 1].
Here the existence of the infinitly small interval is necessary because if it doesn't exist then any interval bigger doesn't exist and finaly any Real interval can't exist, Math should be false.
This is obviously not the case then the Infinitly small interval must exist.
Curiously the infinitly small interval is the only interval smaler than itself. Very similar to God cause of itself in the proof of its existence.