There is nothing that exists in this world which was not created or manufactured. Everything in the world has a manufacturer. Every technological innovation has a source. No sane person will believe that there are materials in this world which does not have a manufacturer. Whatever we are using, we know that it was created.
In the same way, there is no sane person who will not believe in the existence of God. It is foolishness to reject the existence of God. The Bible confirms so. It says that the fool is the one who says in his heart that there is no God. So, those people who are refusing to accept the existence of God are the foolish ones.
Everything that exists in the world come into existence because of a Creator. The Creator of the universe created everything which we are seeing. We cannot deny that these amazing works of creation do not have a Creator. The things which we are seeing were formed by an excellent architect. God is the Creator of the whole world. So, there is a God.