This is something I have pondered on for years.  I believe that there is one God which has always existed outside of time and space, within this there are most possibly lesser gods or beings.  When you talk about 'all is one' this is something I have personally felt, but I believe that there is still an intrinsic individuality to us.  I think about the trinity, three beings separate yet the same.  I believe that after death we will be a part of this union, so in a sense we will all be joined, yet God is still not us per se. 

It is strange to think of God making a mistake, since God is omniscient then a mistake would have been deliberately made, contradictory I know yet I believe 'us' to be that mistake.  When I think about the destruction we have wrecked upon the world (God's own creation), I become ashamed of who we are.  We not only hurt our own kind in the most horrible ways but everything else as well.  That is free will though, or awareness, we are aware of others to such a degree we become selfish and all that is derived from that want.  Yet we emanate from God, so this was all foreseen and allowed...