Aizen = Lucifer???
It's not uncommon for a Bleach fan to compare Aizen with Lucifer, the fallen angel in Christian theology who was cast down to hell to rule until the day of judgment. Being thought of at first to be a kind captain of squad five, he turned out to be a master manipulator just so he can get the Hogyoku from Urahara and wage war against Seireitei.
His ultimate goal being to create the Soul King's key and kill the Soul King, it's reminiscent of how Lucifer intended to rally all the other fallen angels to wage war against the Christian God. He managed to gather some of the strongest hollows he can find and turn them into Arrancar (which probably makes them the demons?)
But what's interesting, and I think Kubo was also planning to reveal it as well, is that Aizen is actually the good guy and what he was doing all this time is just necessary evil. Too bad Bleach got cancelled before I can verify that theory >.<
To make this parallel, we have seen through freedom of expression how some writers have different interpretations about Lucifer. How he was misunderstood and just trying to make sense of things out of the ambiguities of a higher power. Similar to the infamous words Aizen said to Urahara: How can you submit to that thing? (Soul King)
Lastly, in the old testament it was Michael who sent Satan back to Hell. So I guess you can say that Urahara is comparable to Michael the archangel?