Ever since Einstein theoretical physicists have made the point that there is ‘nothing’ outside the cosmos.
Indeed, Carlo Rovelli makes the point explicitly in his latest book The Order of Time — that there’s no point in asking what exists outside of space and time, by which he is possibly really stating something rather tautological: that there is no space and time outside of space and time.
And when one delves into the nitty-gritty of the theory he most closely adheres to — Loop Quantum Gravity — one discovers that there isn’t really any space or time inside either, as both are relative phenomena that manifest themselves subjectively as a result of the networked behaviour of particles.
It’s not an atheistic position per se, failing to fully deter the religiously-minded, as they tend not to be looking for the Divine within space and time. And rather than agreeing that there is nothing on the outside, they’d be more inclined to assert it is where one would find everything — a perfect, absolute, first cause.
This is actually a key point that Richard Dawkins doesn’t seem to get. It strikes me that it reveals how — perhaps counter-intuitively — the biological sciences are not the ideal stick with which to whack religion, because their perspective on our predicament is essentially internal to the system. (Hence all that nonsense about giant spaghetti monsters.)
Theoretical physics on the other hand is poking ever closer to metaphysics, and often in ways which parallel religious perspectives. The Big Bang for example can be spun to resemble a moment of ‘creation’.
The pantheism/monism of Baruch Spinoza is another way of spinning the problem.
Like many modern scientists, he believed it would be a total waste of time to talk of transcendent realms outside the cosmos, to hold out for eternal spiritual stuff to counteract contingent material stuff.
Spinoza instead thought of the cosmos itself as the absolute, as a kind of God, albeit an indifferent one. For him the absolute and the contingent, time and eternity are all part of the same system, but it is our human condition to only experience the bits, not the whole.
However, there’s another way of addressing contemporary theoretical physics which is significantly more encouraging for unbelievers. In this view the hidden, fundamental reality is not perfect order, but perfect disorder such that everything we experience is a pattern that has somehow emerged from chaos and is steadily returning to it.
One can insist that evolution is directionless and purposeless, as it most assuredly is, but the fact remains that it is bucking the more universal trend towards ever greater disorder.