Good summary.Agreed.
As others have pointed out, where religion is concerned, the primary religion in the US is Christian. Rebellious teenagers and 20somethings would focus on Christianity to express their angst. Calling Jesus a "zombie" or otherwise denigrating Christianity is equal to political rebellious behavior like denigrating the flag or blaming the US for all the ills of the world.
Likewise, since "whites" constitute 72% of the population**, it fits that most militant atheists would be white. A little deeper dive would reveal they are also mostly upper middle-class. That doesn't explain the militancy, only the higher number of atheists and agnostics since, IMO, it implies higher education. https://www.pewresearch.org/short-reads/2016/10/11/how-income-varies-among-u-s-religious-groups/
Males tend to be more aggressive although there's a debate about how much is genetic and how much is cultural. https://pmc.ncbi.nlm.nih.gov/articles/PMC6318556/
Normal people outgrow their rebellious natures, but that doesn't convert them to any particular belief system.
**it's more accurate these days, and in the near future, to label it "white culture" AKA Euro-American culture versus asserting it by skin-tone.
Even accounting for demographic racial percentages, I thought that white Euro-Americans were just more likely to be atheist than other ethnic groups.
Once when I asked this question to a JPP atheist (I think it was Perry) they implied white males happened to be more atheist because they are just more intelligent and rational. They quickly realized what they were saying and back tracked, lol


Space-Time began with the Big Bang. Since you seem confused on this point, let me help you: