We have just one word for the end of The Godfather.

Oof.

Here's what's happening. (If you haven't seen it, just watch it. Words just...cannot describe.) Michael is presiding over the baptism of his sister's child. Church music is blasting. Religious imagery is everywhere.

...And a bunch of people are getting brutally murdered.

The scene cuts between Michael in church, hypocritically renouncing the devil, and scenes of all the murders he's ordered. 

We finally get to see what Michael's become and, while it may be impressive, it's definitely not...good.

He's gone from being a war hero and a potential politician or legitimate businessman to being one of the greatest criminals in America, a man who will stop at nothing to support his mafia family's interests. 

It's official: he's fully traveled the length of the anti-hero's journey (see our section on that for more details).

At the very end of the movie, Michael lies to his wife, Kay, about having Carlo killed. This shows that he's set his course: she won't be able to be a part of his real world and will be shut out from seeing his true, ruthless nature in action.

When Michael's capos gather in his office, the door shuts on Kay, ending the movie. It symbolizes the fact that Michael will try to be simultaneously wicked and a loving family man—living an unlivable contradiction. Kay is stuck in the difficult position of loving a man who does evil deeds in secret and locks her out of his actual reality. 

Enter: The Godfather Part II.