>_>
I don't know...
Personally, if it was proven that 'God' did not exist (somehow, theoretically), then I'd probably keep on living the same way I normally do, except being a lot happier considering that I won't have people use religion against me in order to change attributes that cannot be changed (like my beliefs, or sexuality, or 'lifestyle', etc.). In addition to this, the removal of such theist beliefs would mean that churches and places of religious and sacred value would also then either be considered historical (more of a tourist attraction rather than a place of worship), or removed (replaced with increasingly practical buildings for technology and civilization), which may cause a slight outcry of one issue.
Morality.
I'd still try to live my life as ethical as possible, but I assume there will be some people who would lose the hope to live and be forced either to overcome it through various means ('virtual afterlife', physical/emotional compensations, etc.) or crumble under their own pressure and be unable to function. That would probably be quite a scary outcome.
Likewise, if it was proven that 'God' did exist, I'd probably keep on living the same way I normally do, but with contention and frustration. Why on earth would a divinity create certain events/laws/evils? It'd be even more frightening now than ever, because there would be an increase in religious belief (and coerced conversion), which would by definition also cause more tension against those who didn't want to believe in it (and therefore, everyone would be 'normalized' by believing in the 'God').
Free will is then partially removed if one wants to seek 'salvation' of their crimes, as then people would generally follow patterns to seek that final reward rather than figuring out and making decisions to find what they really want in life.
Since I'm agnostic, I tried to look at it in both ways, but if anything, I'd wonder more importantly what would happen if there was a God that was proven to exist... and by proven, it was only referred to in the past tense, in the case that said God was killed by some means. (like a FG XD)