Many people want signs from heaven before they will believe. People in churches who already believe there is a God in heaven, and people from the secular community who do not believe there is a God in heaven, both of them want to see something that proves God exists or something of that sort. Jesus dealt with the problem,
Then the Pharisees came out and began to dispute with Him, seeking from Him a sign from heaven, testing Him. But He sighed deeply in His spirit, and said, “Why does this generation seek a sign? Assuredly, I say to you, no sign shall be given to this generation” (Mark 8.11–12).
Here is the thing. For the secularists, would they truly believe, if the God of heaven suddenly showed a sign, proving once and forever, that He exists? No, I do not believe that they would, because the ultimate sign has already been done, and they still do not believe. It is not enough for them.
The ultimate sign from heaven was God coming down in human flesh to live among us, but people hated Him so much they demanded His crucifixion.