A near perfect allegory for what it takes to make a movie. (And how all the critics illustrate the point perfectly) Here's my interpretation of mother! Major spoilers ahead.
The film is as much about Jesus/The Bible as much as it is about a house. The parallels are there, but I see it way more as a shorthand way to tell the many small allegories that get us to the actual point the movie is trying to make. This movie is autobiographical. I just didn't happen to make it. Aronofsky made it, and it's clearly OF him and the movie is more about making a movie than any movie I've ever seen. I repeat, this movie only uses religious elements to help tell the story and inform the situations. That is not what it is about.
The mother! (as played by Jennifer Lawrence) is actually Aronofsky trying to make a film. He is slowly toiling away, rebuilding the house since the last time a film was made. He is working hard to provide a foundation, but that is only so that it can be torn down again when that all happens.
Him (as played by Javier Bardem) is the screenplay itself. It is powerful, noble, and loyal, but it is not owned by anyone but itself. Especially not its creator (Aronofsky or the mother.)
ACT 1: Him toils to be a thing. It can't write, it can't find the words since the last time it burnt down, but it wants to. So it "lives," it invites "life into this house" and opens itself to turmoil and passion and the outside world. Through a series of cause and effect and Cain and Abel symbolism and Michelle Pfeiffer's character being a rude house guest, all this stuff happens which results in "The film" and "The filmmaker" making love and creating a baby. mother wakes up and knows she is pregnant. i.e. she has an idea. Inspirado! Immediately thereafter the film starts writing itself (Him) starts writing feverishly and much as anyone who has created a thing knows, the piece itself will dictate and determine where it wants to go. As a creative, it's best (and sometimes the only option) to be the shepherd for the piece. You ultimately have to allow for the story to grow and become a thing on its own. Trying to make it exactly what you want will only open it up to be nothing that you want. Michelle Pfeiffer can be very mean and forward about making a new "baby" because she isn't talking about a human life, she's talking about Aronofsky's next film. Which, to be honest, is exactly what happens. The moment you walk out of a theater after watching the premiere showing of your latest film, people will ask you how long it will take to get the next one. The appetite is insatiable. People don't talk about babies that way, but they have no problem with talking about pieces of art that way.
ACT 2: Through furious bouts of creation the screenplay has been written, it is in the hands of the masses (agents, producers, potential distributors, adoring fans) and very quickly, the screenplay itself gets overwhelmed. It is its own entity. Its creator (mother) tries to keep it to itself but it can't. It no longer owns it even though "you're the inspiration." So the script for the film itself is ripped away and goes rogue. It LOVES the attention. And the whole process gets more and more feverish. Crazy things happen while that baby is gestating, which is the actual completed film waiting to be. If you've seen the movie, you know that IT GETS BONKERS. It becomes a literal battlefield. This is the filmmaking process. This actually doesn't even take that long. The time-lines pretty much make sense. The filmmaker is being battered and beaten up and tossed around during this process. But he/she desperately wants to hold onto the baby (which is the actual completed film). Simultaneously he/she wants to retain his connection to the screenplay and everything it embodies.
ACT 3: So there they sit, silent, in a room. It actually takes well over a day, which is longer than it took to get shot, because that all basically happened in one night. The mother holds onto her baby. She is nursing it and trying her absolute best to hold onto it. To keep it her own for as long as possible and protect it from the outside world. But the end of this story is inevitable. The film is ripped from her hands and given to the masses. They have waited so long for this moment. And what do they do this entity? This finished baby that they have all taken ownership over? They literally rip it to shreds. They eat it. They own it now. They have consumed it and torn it to pieces. He/she doesn't own it at all anymore.
Then the world collapses on itself. The house that was built for this story burns down to the ground. An explosion of fire makes it so that the only option is to start from scratch again. And it will happen... the screenplay, the film, the creation, must start anew. In the ashes there is a diamond, a crystal, a small world of hope. This contains the Inspirado for the next one.
Soon, the mother returns. She is different, but she is the same. And the process begins itself anew.