Yes, I do hear myself, and I am a MIGHTY GOD. Not just good. He didn't want it all for himself, if you remember his insane rantings about how the not pure people (basically everyone other than the ancients which is.. basically everyone 'cept Aeris) would destroy the promised land because of their impurities, He wanted all of them to die because they didn't deserve to go to the promised land. Kill all the impurities, in his head, You'd only have him by default. The reason he killed Aeris is because she posed as a threat to him, he wanted to smash a meteor into the planet because he knew the planet would gush with the lifestream and if he could get all that power he -could- become a god, and with his thinkings, Gods can get into the promised land because they're as holy and pure as the ancients once were.
He wanted to destroy the planet, not the promised land, In his head these are two different things. Go back to the game, disc one perferably and read his ramblings in depth about how "Clouds ancestors ran and hid in shelters while the ancients fought" and what not, He hates the 'impurities' living because they are not good enough to make it into the Promised Land, only the ancients. And no one can say "Well he killed Aeris and she was an ancient" yeah she was, but Sephiroth -was- human, so she posed as a threat, he killed her as simple as that.
The idea of 'promised Land' can be interperted by the gamer, it's not like you could look on the world map for 'promised land' and find it, it's obviously not the lifestream because as we saw with cloud, that doesn't really help to much. My idea of the 'Promised Land' is much like Heaven should be, the purest get in. Ironically in FF7 the lifestream was as pure as you get, and if Sephiroth could use that he could get in the promised land. I don't believe the planet itself was the promised land by anymeans.