Original Sin

Why do Christians (most denominations, at least), and certainly our country in general, have a view of people as inherently flawed -- fallen, sinners -- by nature? Christians have this as a part of a the fundamental creation story, from the very beginning, with Jesus as the path to at least partial redemption.

What about other religions? I think Judaism and Islam do not have the same concept of "original sin".
Judaism: The term “original sin” is unknown to the Jewish Scriptures, and the Church’s teachings on this doctrine are antithetical to the core principles of the Torah and its prophets.

Islam: The concept of original sin simply does not exist in Islam, and never has, but no great notion of inherent virtue either.  Also has no notion of evil thoughts as sin:  "good thoughts are not always the first instinct of humankind. As such, the Islamic understanding is that the very conception of good deeds is worthy of reward, even if not acted upon. When a person actually commits a good deed, Allah multiplies the reward even further."

Hindu: There is no concept of original sin in Hinduism. It is an aspect of a duality, its opposite being virtue or dharma. 

Taoism:  While English lexically differentiates theological sin from legal crime, the Chinese language uses one word zui 罪 meaning "crime; guilt; misconduct; sin; fault; blame." 

Buddhism: The problem with original sin or mistake is that it acts very much as a hindrance to people. At some point it is of course necessary to realize one’s shortcomings. But if one goes too far with that, it kills any inspiration and can destroy one’s vision as well. So in that way, it really is not helpful, and in fact it seems unnecessary

In any case, even in the secular US people tend to believe that people are inherently flawed. Why?

Well, for churches, if all believe that people are born sinful, but "we" now are not, that makes for powerful in-group signaling. Plus, it means others are fallen, and that provides opportunity for opinionated evangelism "we NEED to save them" & "you're going to hell" as motivation, & (importantly) more virtue signaling to the in-group with "good works" as you proselytize to the out-group.  Best of all, you can tie evangelism strings to every charitable gift or outreach.

Believing that all are born "of the devil" also demeans, automatically "othering" the out-group, as capable of ANYTHING evil, and that's an important step in being able to oppress, take from, and even kill them if required. It's not a small feature, if you look at western imperialism & the ongoing justifications of land-taking, slavery, and oppression over the centuries.

From psychology experiments and empirical experience, we can confidently say that it's hard to convince people to do harm to those "like us", but it's pretty easy to get people to do pretty evil acts if you have a "higher calling" for people to sign-up to serve.  It's even easier if the intended victims are seen as a threat, undeserving, evil, or not quite human.

Still, I think this is not the worst part, which is that for the average person a pervasive view that other people, and even themselves, have an in-born bias to evil does a lot of psychological damage.  It means that we are predisposed to presume negative motivations (even more than our in-built Fundamental Attribution Error tendencies already do), and we have some license to behave badly ourselves when it suits us, or to act holier-than-though if that better suits.  We have top-cover to immediately think the worst of people, or to justify it, as our desires warrant.  And, with no real basis for it, I'll suggest that perhaps avoiding sin is like learning to ride a bike and trying to avoid trees or mailboxes:  the harder you focus on the tree you DON'T want to hit, the more you steer directly toward it.

- Homeless?  Probably the wages of sin.

- Drug addicted?  Fallen nature taking root.

- Speeding in a school zone?  All have fallen short.

- Find cash in a dropped wallet?  The wealth of the sinner is laid up for the just.

- Pastor molests a child?  Terrible, but the devil targets pastors through their flesh.

- Disciplining a kid?  Spare the rod, spoil the child - beat the devil out of them!

- I want to spend the rent money on an Xbox?  The flesh strikes again!

For the non-religious, the heavy Christian bias of the US makes some of this foundational thinking sink in even without embracing the religious tenets.  "People suck" is easy to believe.  Every stranger is a threat, and any slowly creeping car captured on your Ring doorbell is casing your house.  Add a few more of our brain faults, like confirmation bias, recency bias, and loss aversion, and we're well on our way to paranoia.