Existence of God

In my opinion, the strongest argument for the existence of God is similar to the common argument for the existence of extra-terrestrial life, ie. even if the probabibility of life emerging at any given time on any given planet is infinitesimal, because there are billions of galaxies with billions of planets that have existed for billions years, the odds of life developing many times over are high.
(I don't think this argument is entirely solid, but it serves it's purpose)
By the same sort of thinking, if life is probably appearing in various places throughout the cosmos, it is likely some beings have evolved, either organically or through their own bio-engineering to have a strong enough understanding and control over the properties of the Universe to be what we might consider a 'God'.
Of course this wouldn't be like the standard conception of God that many religions hold: a being which has existed forever and created the universe. (although if the multi-verse theory is true, perhaps this being, or group of beings come to be in another universe and created our particular one). However, it would would be a God familiar to Latter Day Saints, ie. a being (or group of beings) that through time and work progressed to 'deification', and for whatever reason has taken an interest in our well being, either as creator, or merely observer.
Perhaps these beings would have an interest in helping other creatures become like they are. They may have learned to extend life and capture 'souls' and when we die would take us to a wonderful place where we continue to grow.
Or if we are something like a simulation running on their computers, so that as far as we are concerned, they created us and our Universe, when our virtual selves die we could go to a virtual heaven and exist for as long as they kept their programs running.

Even if such beings did exist, there is no saying what their nature would be like. They might be empathetic and loving, malicious and brutal, or indifferent.
Of course, perhaps the ways our universe can be manipulated are far more limited and no being, even in theory could ever achieve enough power to be anything close to what we would consider a God.