Exactly. This is the dilemma that man finds himself in.
Atheistic philosophy cannot in and of itself distinguish right from wrong.
And yet, man is a sinner, and by nature will not follow God's natural law.
The wisest course in setting up a system of government is that which the Founders attempted to take, recognizing at the same time the principles that (1) all men are sinners, and therefore extensive checks and balances are needed to be built into the system by which laws originate in order to mitigate this and (2) ultimately the moral validity of all laws rests on God's natural law, and when government becomes too far removed from that (not for light or transient causes), the people retain the right to reform their law-making institutions.
The premise here is that this concept works well only when the people have a respect for God's natural law; if not, one ends up not with the American Revolution, but with the French, or worse.
Nonsense. Any rational creature can discover common societal norms that when enforced bring a joint mutual benefit. You might personally find that too morally hollow for your tastes, but it leads to a set of laws similar to those discovered by the biblical writers.
You are wrong here. Believe me when I say an Atheist can distinguish right from wrong, often much better than many professed Christians I have known.
Both Buddhism and Taoism are non "thiestic" religious philosophies (religions), and each contain mechanisms for distinguishing right from wrong.