Could he have saved mankind in any other way while simultaneously being congruent with his own character?
Or could he have simply forsaken mankind while being consistent with his righteousness?
I honestly can't answer those questions, but I suppose a "no" is possible.
Jesus proved, by his righteousness, that mankind was salvageable.. If God couldn't live righteously in the flesh, then man is an utter failure of a creation. Sure the omniscient, omnipotent God knows, by his omniscience that on his holy drawing board, he knew that man was theoretically salvageable. But what is knowledge or theory or hypotheticals if they aren't put into practice? It's a tree without fruit. God is not a tree without fruit- he is the root of all fruit.
So I think he "had" or "needed" to do it- not because of some external force or demand on him- but he made himself do it, simply because it was the right thing to do, based on what he had already decided was right. If he, as god, requires certain things of mankind, then he ought to demonstrate that those things that are required could even possibly be done. Otherwise how could he condemn anyone? No one would confess that he truly is Lord, because they would say he demanded things that were impossible.
But the bible says that every tongue will confess that he is Lord.
Can you imagine that? "every tongue" seems like it would even include the people about to be thrown into the Lake of Fire. How else will they confess unless it is proven to them? People knowing that they are going to ETERNAL DESTRUCTION are gonna concede.
I COULDN'T EVEN IMAGINE THAT!!! If someone was gonna send me to eternal destruction, I'd be like "NO WAY, YOUR NOT LORD". The only way to make me to confess, was to prove without any doubt so that i was convinced that I was a total douchebag, and deserved eternal destruction- so that even when offered a way out of eternal destruction- I am the one that turned it down, and chose eternal destruction for myself.
If he didn't he would get no glory from his creation at all, and everything would be a waste. Is a wasteful god, a perfect holy god?
I'm not really 100% sure of this train of thought on the matter that I have going, but I think it's pretty sound that everything that God has done was done because it was of necessity. But even the necessity of the things needing to be done was necessitated by God himself. If that makes any sense.