Let us play a game.
Let us suppose that there is a creator of this universe. If this creator is to keep proof of his existence in the created world in such a way that it can be easily recognized as proof of a creator, then which proof will he keep?
Anybody can play this game, theists and atheists alike, because it starts with a supposition only.
Here is a hint for those who will take part in this game: A creator as a creator may have some particular properties which no one else, nothing else created by him may have, simply because they have been created and because they are not the creator. If we now find these particular properties of a creator in something created, then we will immediately understand that these are from the creator only because no created thing can naturally have those properties.
Here is one more hint: When we say about something that it is spaceless and timeless, what we mean to say about it is that it is not within any space and time. But, whatever is there in the universe, is within the space and time of the universe. Being within the space and time of the universe, can anything naturally be spaceless and timeless?
Here is one more: If there is indeed a creator of this universe, then it can be said that this creator has brought everyone and everything within the universe into existence. Whatever has been brought into existence by the creator has been given certain lifetime. Many stars in the sky have a lifetime of several billion years; we human beings have a lifetime of a few decades; some insects have a lifetime of a single day only. Can we think of anything that has also been brought into existence by the creator, but that has been given no lifetime?
When anybody playing this game will be able to correctly pinpoint those particular properties that only a creator is privileged to have, this game will be over.
Because then she will come to know that there is a God.
Proving the existence of God is so easy, yet so difficult.