The fulfillment of biblical prophecies is reliable proof that the God of those who were inspired to write them exists, knows the future and can also shape it as He pleases.
Is. 41:23 Tell us what will happen in the future, So that we may know that you are gods. Yes, do something, good or bad, So that we may be amazed when we see it.
...42:9 See, the first things have come to pass; Now I am declaring new things. Before they spring up, I tell you about them.
... 43:19 Look! I am doing something new; Even now it is springing up. Do you not recognize it? I will make a way through the wilderness And rivers through the desert.