Fine if you want to just believe but look at what you posted

the stories about the Jesus god are old stores written thousands of years ago just like the other stories about resurrections from the dead.

And of course no one was there when the universe began to expand BUT there have been many studies that are able to look back at the evidence of that expansion as found if many things still occurring in the universe.

The 'snow' on your TV is evidence of the Big Bang theory and if you look around there is lots of info about how science has determined that to be the best explanation

A quick search found this site which seems to lay out the evidence and when it was found all confirming the theory.
I am sure there is lots more info and probably much more detailed but this will get you started in your search for those witnesses of the Big Bang.

https://www.uwa.edu.au/science/-/media/Faculties/Science/Docs/Evidence-for-the-Big-Bang.pdf