But everybody believes what they are doing is morally right, no matter what side they are on.
I think the left is actually rejecting any notion of morality as a guide. Morality is based upon "higher" principles to which the left does not subscribe.
A lefty is guided by his or her own desires, period! Do not try to tell them there is a higher power who has made rules to govern our lives.
I disagrees, people do things every day that are less than morally right to some degree both deliberately with full knowledge or by rationalize to justify there actions
To me the concept of original sin is to morally as the Socrates concept of wisdom is to knowledge
You accept that the path to wisdom is to acknowledge your ignorance nature
You accept that the path to morally right is to acknowledge your immorally (fallen) nature
In both cases the best you can do it go as far as you can it the right direction, to follow, accepting that there is perfect wisdom, perfect knowledge, perfect truth, and knowing we can never reach that perfection and will fall far, far short
Our saving grace is to follow and quest for what is truth external to mans corrupt nature
To follow the dictates the moral compass not the whims of men
"But everybody believes what they are doing is morally right, no matter what side they are on."
At the time of the founding, and for generations after, America had a broad consensus of what constituted right and wrong. There were gaping differences,to be sure, as with slavery. But the fact is, until very recently, in America, some things simply were considered indefensible. And some things simply went without saying.
Unfortunately, largely due to the leftist sabotage from the 60's on, that sweep of consensus has been deliberately eroded.
Now, nothing can be assumed, nothing can safely be left to "go without saying." As a result, everything is up for grabs including the definitions of common words (like "marriage") and the definition of the virtues, which have been understood since antiquity.
So, what you say is true today, and illustrative of a severe problem in our culture.
It was not always so.