It is amazing what some people demand of God in order for them to believe in Him. Matt 27.39-44. Mark 8.11-12. News flash! It isn't supposed to be that way! God created mankind and the world and He gives us life and goodness daily. Acts 17.24-28. Therefore, He doesn't have to prove anything to man; instead it's the other way around, man needs to do some proving to God. Romans 9.20-21.
Man can start proving being worthy of God by simply accepting and believing that He is. Hebrew 11:6 1 Peter 1:8-9. This is all man needs to do and this is all God needs to allow.
As His creation, we owe Him all the respect that we can muster up and we don't need to insult Him by making some foolish statement challenging Him to do something to convince us of His existence.