The Bible said in the book of John, God is a spirit and they that worship Him must worship Him in spirit and in truth. That we can't see or touch God doesn't mean He does not exist no, He is a spirit .
The proof that God exist is seen everywhere in our everyday living.
Have you wondered how the earth was formed? Have you ever wondered how every living thing produces it kind?
Have you ever wondered who made the great mountains and the seas. Which man has that kind of ability to create something like that.
The proof that God exists is likened to the air we breathe. Can we see the air with our physical eyes? No. Can we touch it, no we can't but does it exist, yes that's exactly how to explain the existence of God. God exists and He has been in the business of doing some great and wonderful things to those who believe that He exists.