Ultimately this is a Job story. And on that level i get it fairly plainly. As i type this im still working out things so this might get very convoluted. The symbolism is where i think a lot of the depth is. The protagonist is a mathematician. Which is a person who understands things and minutiae of them.
The first time we meet him he's doing a lecture explaining Schrodinger's equation. A student fails the midderm on the topic and says to the extent "i understood the cat its the math i dont get." To which the protag replies "its about the math no one understands the cat." He understands the how but the metaphysical is lost on him. This scene is the film laid bare i think. Inside this scene he also lays out his moral paradigm which he will later betray.
There's also the trips to the Rabbis and i think both of them give us the morals truth as well. The protag is flummoxed by their responses. Finds them completely useless and the audience does too. The first tells him to look for God in the mundane. To appreciate it him through the eyes of an alien. The second tells a, long winded and highly entertaining, story about a dentist. At the end the protag asks what was the point of the story. The rabbi is befuddled by the inquiry and shruggingly says "doing good couldnt hurt?" As if he'd genuinely never considered there was a point in the first place.
So when we arrive at the climax and the protag, in an attempt to climb out the ever deepening hole life is digging for him, betrays his morals it brings the truest wrath. The point is the same here as it is in Job. Do good for goodness sake; not for reward. This film then says and dont do evil; or else.
And in that:
A Serious Man (2009) - 7/10