One of the core doctrines of Biblical Christianity is that the human spirit is NOT inherently good.
Please note that "good" is not the same as "nice," "sociable," or "loving." "Good" hates "evil," even when evil is mild, and to ones own benefit.
Excellent point. And that Judeo-Christian worldview of the sinfulness of fallen man contributed to the checks and balances, separation of powers, and Constitutional governance that this nation was founded on. The Founders knew that power corrupts, and so they built in checks to that temptation.
A person can’t understand what this country is and why it flourished when it remained true to its Judeo-Christian roots, without understanding those roots, which also happen to make sense out of history.