I will prove to you that God exists

[Sheldon]

No, I pointed you to a book (one of many) written by an atheist scientist that points to the fine-tuning of the universe (using well established scientific facts) 

You have presented no evidence the ideas expressed are scientifically evidenced, and we already know they are not, as there is no such consensus among scientists with the necessary expertise in the related fields of scientific study. And of course, if this man remains an atheist, this rather contradicts your assumptions fine tuning evidences a deity. You see happy to ignore such flaws in your spiel. 

and claims as a result he concludes we live in a multiverse. He rejects the idea a universe with the properties for life could occur given one shot. Debaters are supposed to cite authorities to support their point of view. Who should I quote Alfred E. Nueman? 

Claims see, the subjective opinions of a scientist, are not accepted scientific ideas, hence the appeal to authority. 

Fine-tuned universe

The fine-tuned universe is the hypothesis that, because "life as we know it" could not exist if the constants of nature – such as the electron charge, the gravitational constant and others – had been even slightly different, the universe must be tuned specifically for life.[1][2][3][4] In practice, this hypothesis is formulated in terms of dimensionless physical constants.[5]

I now what the term means thanks, it is not broadly accepted among elite scientists in the necessary fields of study that the universe is "fine tuned", or that this phenomenon is evidence of a creator or a deity. Do you imagine this objection will go away if you simply keep repeating your original claims? That scientists use the term "fine tuned" to describe this phenomenon, does not mean it is fine tuned, let alone by a creator, or a deity. You seem to have lathered yourself up, but forgotten to turn on the shower. I accept that the carbon based organic life we observe, would be impossible if the parameters of certain characteristics of the physical universe were shifting an infinitesimally small amount, this does not represent scientific evidence it was fine tuned, even if that term has become a popular metaphor among scientists to describe that phenomenon.  

There is sufficient evidence...there is evidence powerful enough it leads several atheist scientists to stake their reputation and conclude we live in a multiverse 

I meant sufficient for it to be an accepted scientific idea that the universe has been fine tuned, and there demonstrably is not, as there is no such consensus, the opinions of a few scientists is not is not how scientific ideas are validated. The term fine tuned means something scientifically, just not what you are assuming. 

Lastly we're justified to assume the existence of the universe was either caused intentionally or was caused unintentionally by mindless natural forces. That's what you assume isn't it?

Ah, so can't explain why you assume fine tuning is evidence of a creator deity, thought so, and all you have is yet another straw man fallacy, as I made no such claim. 

We mere humans have caused the virtual universe to exist using the theistic method of design, planning, programming and engineering. It may only be a matter of time before we can populate the virtual universe with virtual people who experience their reality just as we do. Its not only possible, we may soon be god's of our own virtual worlds.

So no then, you can't demonstrate a shred of objective evidence any deity exists or is possible, again that was my suspicion, but I like to keep an open mind, even after all these years of watching hubristic hyperbolic claims from religious apologists failing to offer a shred of objective evidence any deity exists, or is possible.