If I were an Atheist

[Angrboda]

Its much more than just the existence of gravity. It is the fine balance between the strength of gravity and other forces. If the relative strength of gravity was only a little more or less the universe as we know it would be much different.

An except from Just Six Numbers.

https://sciencebits.wordpress.com/2008/0...-stronger/

Gravitation is feebler than the forces governing the microworld by the number N, about 10exp36. What would happen if it weren’t quite so weak? Imagine, for instance, a universe where gravity was ‘only’ 10EXP30 rather than 10EXP36 feebler than electric forces. Atoms and molecules would behave just as in our actual universe, but objects would not need to be so large before gravity became competitive with the other forces. The number of atoms needed to make a star (a gravitationally bound fusion reactor) would be a billion times less in this imagined universe. Planet masses would also be scaled down by a billion. Irrespective of whether these planets could retain steady orbits, the strength of gravity would stunt the evolutionary potential on them. In an imaginary strong-gravity world, even insects would need thick legs to support them, and no animals could get much larger. Gravity would crush anything as large as ourselves.

I thought we'd been over this already.  As Don Tow observes in his review of Rees' book:

We can conclude that instead of having 36 zeros after 1 in the value of N, if there were only 30 zeros after 1, then the universe would be very much different from the current universe, and life as we know it would not be able to exist. Note: On the other hand, if the gravitational force were even weaker, i.e., if N is even larger (having more than 36 zeros after 1), then it would take longer to form galactic structure, and galactic structures would be less densely populated, and larger and perhaps more complex life organisms, different from current life organisms, could exist.

http://www.dontow.com/2010/01/review-of-...-universe/ (emphasis mine)

So in other words, it's only fine tuned if you only look at it from one side.  From the other side of variation, life indeed could exist.  That's not fine tuning.  That's selective vision.

And while we're at it, Victor Stenger has run simulations in which the parameters of the universe varied by up to two orders of magnitude, and half of those universes yielded long period universes with heavy elements capable for the support of life as we know it. A point that was brought up early in your first run at this argument (this is round 4). So while the parameters in this region of parameter space may be sensitive to variation, it's clear that there exist in that entire parameter space other viable solutions which could support life. It would seem things are not so fine tuned as Martin Rees would have us believe.