I hope you’re not the anon with the project for class, asking me to do your homework for you! But I do want to answer this, so you get my opinion, which may not be the actual answer.
I think there’s more than one climax, depending on what your reading of IWTV focuses on. I’m not as religious as some ppl, so I don’t give that theme as much weight as other readers might. And that is a huge aspect of Louis’ struggle with vampiring and giving into his vampire nature, being in direct conflict with the most important of commandments, Thou Shalt Not Kill (in conjunction with Thou Shalt Not Steal, bc this kind of killing is doing both).
Here’s one definition I found for climax, the noun: “the most intense, exciting, or important point of something; a culmination or apex.” For me, that moment could be a catalyst, too, changing a character to some extent, could be a drastic re-calibration of their inner dialogue with themselves, reconfiguration of their moral values, etc.
I’m not quite sure which scene in IWTV (book or movie) that would be for you, but for me, one of the most intense moments was when Louis found Madeleine and Claudia’s ashes:

First is denial.


It’s in this moment that Louis has lost the most precious person, the one who’s told him what to do, someone he could worship and follow, someone who metered out his doses of happiness with her approval.
He’s also lost his own
(and very first!)
fledgling, and even though in both the book and the movie there doesn’t appear to be much attachment to between them, @vampchronfic/@gairid‘s headcanons about that have convinced me that there IS a bond, deep and invisible, created in the act of turning. Maker and fledgling are drawn together. Something like the attachment between a mother and her child, perhaps more powerful bc (hopefully) the giving of the Dark Gift was a consensual act between adults. It’s even more cruel in the movie bc she dies the same night she was turned, talk about bad life choices.
ANYWAY.

He holds off on the anger for now, goes straight to bargaining. He reaches out to touch them, maybe he thinks there’s some way to save them still? Or maybe the ashes are just on the surface, maybe Claudia and Madeleine are still intact under there? It feels like a nightmare and he wants to prove it’s not real.

But it is real, and they crumble, and everything that they were is gone.

This, his lightest touch, it’s heartbreaking, their final destruction at his own hand ;A;

Depression and acceptance. It’s real, they’re beyond saving, he’s failed them both in so many ways. The only thing left is (anger stage) revenge against this injustice, against the Theatre troupe, and once that’s accomplished, against himself.
So I’d say this was a climax bc it acted as a catalyst for Louis, he finally burst into action because of this, and any remaining illusions he had about vampiring and immortality were shattered. He’s 1,000% done and he’s gonna go out in a blaze of fiery glory punishment.