I hope this doesn't count as derailment, but I'd like to chip in and agree with Mariela here-- I think it would be wonderful to have just one alignment, the alignment we see, and have it change with our actions. That way if we're trying to play a certain alignment and failing at it, we can try to change how we're playing.
I've tried to keep some of my characters on alignment by looking at my resistance to mind magics, which I vaguely think might change if I stray from it, but I would feel much better just having a direct line of feedback-- and, better, yet, having the alignment of my character determined by my actions, so I don't pick the wrong one at character gen because I'm not sure how my character will develop. Heck, I think it would be awesome if everyone started out as true neutral-- or maybe a step away from that to reflect their back story-- and only their actions could maintain that alignment or make them ping as good or evil.
I also think it would be just as effective and a good bit easier for the players if only characters dedicated to a God had to worry about staying within a certain alignment range. It makes sense, I think-- if you serve a certain God you'll want to be very careful about being a good follower and not upsetting that God, but if you're just hanging around the Kingdoms without a patron, it seems a little weird to have a set alignment that you can't just up and decide to stray from a little bit. Granted, a complete turnaround may be unusual-- but it would take a good bit of effort to change one's alignment from chaotic evil to lawful good anyway, and if there were some kind of "alignment log" then any God someone tries to join later on could see the stains on their soul (if they exist) and question the circumstances under which the character behaved so out of line with the belief structure they want to follow now.