can someone please help explain the dialogue from this movie? So this is how the dialogue goes:

Person X: Let's say there is no God, and each man is free to do what he chooses. What prevents you from murdering somebody?

Person Y: Murder's immoral.

Person X: But immorality's subjective.

Person Y: Yes, but subjectivity is objective.

Person X: Not in a rational scheme of perception.

Person Y: But perception is irrational. It implies immanence.

First off, with "Subjectivity (the act of being persuaded by opinions) is objective (being persuaded by facts)" how the hell would that work? Aren't they antonyms? And is person X saying that it's not rational to perceive subjectivity as objective or that people with rational perception are influenced by opinions and not facts? And then what does it mean when they say perception implies immanence (the quality of being inherent or within), I can't even begin to comprehend what they're saying. Someone please help explain this to me!

To explain it you would have to accept it. I don't, starting with the first sentence. We are free to do what we choose, within the limits of our bodies and minds. All societies have laws. Most societies have laws against murder. Murder can get a little murky in regards to things such as self defense, protecting someone, or revenge.

Most of this is a bunch of meaningless word play. Why do you feel that it is worth trying to dissect?
Subjectivity is not objective just because it exist.
We can only try to reach a rational scheme of perception. It's on a sliding scale of perfection.
Irrational is not a good description of perception. Perception IS subjective.
Immanence is not a word I use. I see it used in religious discussion. It's too vague and metaphysical for me.

So... why is this tripe important to you?

It's because although I might not agree with what they're saying, I at least want to understand their position.

I am confused by your question. What is it you do not understand about the blabbering of two humans in a movie?