When the nation of Japan researches the cause of it's constant tsunamis — it awakens Godzilla, deep in the Pacific, who arises and establishes an authoritarian rule over it's country as it's citizens build it a throne and serve it as their God leading to a cult-like religious following and the third world war with catastrophic nuclear consequences.

I like the idea of the irony - They want to stop/prevent tsunamis, a kinda natural world monster, they actually awaken a real monster.

For me, I would try and condense down the logline:

In an attempt to better protect its people from tsunamis, Japan accidentally awakens the monster Godzilla, which starts rampaging through the city.

You could perhaps replace Japan, with the name of your protagonist EG. Japanese researcher John Doe accidentally...

They doesn't have to be American. But you DEFINITELY need a protagonist for this story to follow. What's the through line? What am I meant to care about?

You don't need to describe Japan as "the nation of Japan". Just say Japan.

Is Godzilla substantially more intelligent, or the Japanese substantially less intelligent, in this iteration of the story? How does a giant lizard, taller than most skyscrapers, unable to talk, establish anything resembling authoritarian rule over Japan, a technologically advanced society that currently worship a diverse range of deities (or not) across its citizenry?

I would suggest, if you're serious about writing this (as Tor says below, they've just rebooted Godzilla, so I'm pretty sure no one is looking for spec scripts for Godzilla at the moment, let alone the copyright issues you're likely to face) I'd suggest changing the character to either an original giant-monster-from-the-deep, or else go with something like Cthulhu, which not only hasn't had a worthy film adaptation yet, but also already has a cult-like following built into its mythology.

As far as the logline you've submitted, it's missing most of the essential parts of a logline and reads more like a short concept pitch - not even really a synopsis, as I have no idea what actually happens in your movie. Do these events occur before the movie begins, are they the catalyst for the story, or do you track the rise and rise of this monster and the war?

Hi Caleb,

Godzilla is a registered character and I would suggest creating you own kaiju for the purpose of the story. If the Godzilla character could communicate, I would suggest using it in the logline.

"Awoken from the depths of the pacific, a telepathic kaiju must establish an army of humans to protect the shores of Japan from a rival kaiju and it's cruel master."

Hope this helps :)