I wonder how much of this correlates with the drop in religious participation. Religion, for better or worse, was a useful tool for stigmatizing bad behavior and incentivizing good behavior
Or you could argue that their internal culture probably due to religion was not strong enough to fight against external influences.
Sweden is one of the least religious countries in Europe, and one of the safest.
"Approximately 13 percent of the population in Sweden experience problems in their own residential area with crime, violence or vandalism. It is one of the highest proportions in Europe."
https://www.scb.se/hitta-statistik/artiklar/2019/fler-upplev...
Modern America has no common history. America has no common ethnicity, no common roots and now no common religion. The least religious nations are often ethnically homogeneous (Sweden, Korea) or have an incredibly strong national cultural identity of what it means to belong (France, Singapore).The US had neither, and then took down the one thing that held together 80% of the US as of 2000. ie. Christianity (mostly protestant-derived)
And I'm a Hindu-by-birth Atheist immigrant. So, I don't have any vested interest in the restoration of Europe-derived Christianity within the US.
To me, the closest thing to a common american identity is a combination of the following 3:
* Protestant values of hard work, merit and family
* Colorblind-live-and-let-live immigrant melting pot
* Capitalistic enterprising nature of shooting for the moon and that anyone can be a billionaire/President.
Now, these might not be perfect, but it was the closest thing to national values that 80% could get buy in on.
However, populist politics of the last 10 years and the change in wealth distribution post 2000 has seen wholesale rejection of almost all of these values from both the populist left and the populist right. As the nation continues fracturing, the resentment towards your fellow countrymen grows to the point that you feel no civic duty towards your fellow countrymen, and maybe even take joy in looting them.
Religion unites as long as it is homogeneous. High level of religious beliefs would not help much, if they didn't unify people through a collective identity. So in this case, high levels of religious participation would not have helped, because there would still never be any agreement on a common religious identity given the degree of religious heterogeneity.
On an aside, I always find it funny when people say that countries that tolerate heterogenous identities such as the US or India are discriminatory or racist. Yeah, as if you with your 95+% cultural/religious/ethnic homogeneity have any right to speak about diversity. You can already see Europe coming apart at its seams with a small influx of culturally diverse middle-eastern refugees. The friction you see, is a result of an open system that allows each of these incompatible cultural identities to get a voice in the national discourse.
Hindus in India divide and fight amongst themselves based on caste even though they all follow the same religion.
In other words: freedom, equality, justice, democracy, and self-determination.
America's relationship with religion has always been complex. The first amendment simultaneously guarantees the free practice of religion and enshrines its separation from the state; as a government, the U.S. cannot make any law that preferences a particular religion. Many of the founders were Deists, which is a religion that simultaneously accepts the existence of God but also relies upon empiricism, rationality, and individual thought to divine His will. America is also explicitly not Protestant, and the dominant religion varies a lot from place to place. I grew up in New England, which has a Puritan early history but now is populated by largely Catholic Irish & Italian immigrants. My mom's childhood friends in NYC all seemed to be Jewish. In Utah, it's mostly Mormon.
I'd argue that the main reason America is falling apart is that we've forgotten those core values of liberty, equality, justice, democracy, and self-determination. These have always existed in some tension, but right now we're not doing a particularly good job of any of them. Instead the focus is on capitalism, virtue-signalling, protection from outsiders, preferencing your in-group, forcing your particular morality on others, and many other very human but very un-American activities.