Awesome, thank you all for the info!!
Is there a way to see my Warmongering score? I know that in the diplo view it might say "they fear warmongering" or something to that extent. But that is not the same, right? Knowing how much of a penalty I might get when I decide to attack someone would be a great help.
Yes and no. With Transparent Diplomacy enabled, you can view the opinion score for the penalty. You could do some math to figure out how that translates if you were so dedicated.
The anti-warmonger fervor bonus is equal to (your warmonger score / 25), rounded down and capped at a certain value based on difficulty level. Note that the AI and the human can have different caps depending on the difficulty level.
The opinion score is equal to (your warmonger score * AI's WarmongerHate flavor / 20), rounded down. However, you can't know precisely what the WarmongerHate flavor is in any given game. Each leader has an XML value between -1 and 12; it is randomized by up to +/- 2 at the start of each game (+/- 4 if Random Personalities is enabled), and then it is clamped between 1 and 10.
Note that the opinion score determines how much of a threat the AI perceives from your warmongering and therefore how strongly they will react to it diplomatically, but for fairness reasons, the Anti-Warmonger Fervor combat bonus is the same regardless of how high or low their opinion is.
You can roughly tell what the WarmongerHate flavor is based on the description of their attitude towards warmongering in the opinion modifier.
Special Descriptions
(They furiously abhor warmongers.) = Gandhi and Enrico Dandolo, always 10 WarmongerHate
(They are bloodthirsty warmongers!) = Montezuma, always 1 WarmongerHate
Standard Descriptions
(They hate warmongers!) = 9 to 10 WarmongerHate
(They strongly dislike warmongers.) = 7 to 8 WarmongerHate
(They dislike warmongers.) = 5 to 6 WarmongerHate
(They overlook modest warmongering.) = 3 to 4 WarmongerHate
(They ignore most warmongering.) = 1 to 2 WarmongerHate
---
You can also tell in what range the
opinion score is, even without Transparent Diplomacy enabled, from the first part of the message which describes how much of a threat they feel.
They have some early concerns about your warmongering. = Threat level is NONE or MINOR (score < 80; a score of < 20 is NONE, but still shares the same message)
They are wary of the potential threat posed by your warmongering. = Threat level is MAJOR (score between 80 and 139)
They believe your warmongering has become an existential threat. = Threat level is SEVERE (score between 140 and 199)
They fear your warmongering will end this world in fire! = Threat level is CRITICAL (score between 200 and 2,147,483,647)
There is a special exception to the usual rules: if you have conquered - that is to say, killed, captured the capital of, or vassalized - at least 25% of major civs, your threat level will be SEVERE regardless of your score. Every two City-States also counts as one major civ for this.
If you've conquered 33% or more, your threat level will be CRITICAL regardless of your score. These two exceptions don't apply any combat bonus to their units, they only affect diplomacy.