At least to me the entire sentiment seems to fall into 'no true Scotsman' territory under any individual scrutiny. If we take someone's life apart and look at the individual pieces you'll find authentic and inauthentic moments everywhere.
The Christian theological view[0] is that no human is perfect (or good), and it is essentially impossible to be perfectly good, but God still wants us to try to be as perfect as we can humanly can.
The most relevant verses on the idea that we are not good is likely Romans chapter 3, starting from verse 9:
What shall we conclude then? Do we have any advantage? Not at all! For we have already made the charge that Jews and Gentiles alike are all under the power of sin. As it is written:
“There is no one righteous, not even one; there is no one who understands; there is no one who seeks God.
All have turned away, they have together become worthless; there is no one who does good, not even one.”
“Their throats are open graves; their tongues practice deceit.” “The poison of vipers is on their lips.” “Their mouths are full of cursing and bitterness.” “Their feet are swift to shed blood; ruin and misery mark their ways, and the way of peace they do not know.”
“There is no fear of God before their eyes.”
Now we know that whatever the law says, it says to those who are under the law, so that every mouth may be silenced and the whole world held accountable to God. 20 Therefore no one will be declared righteous in God’s sight by the works of the law; rather, through the law we become conscious of our sin.
-- https://www.biblegateway.com/passage/?search=Romans+3&versio... (starting at v. 9)
The call to be perfect:
Be perfect, therefore, as your heavenly Father is perfect. -- Jesus, in Matthew 5:48
Our inauthentic self is forgiven via Christ's sacrifice, which permits us to partake of the new life/creation promised. On the New Creation, see Revelation 21.
[0] For disclosure: yes, I'm a believer.
“Is it really true that political self-interest is nobler somehow than economic self-interest? You know, I think you’re taking a lot of things for granted. Just tell me where in the world you find these angels who are going to organize society for us?”
I wouldn't consider it impolite, but would say it's an unproductive question like all such questions of "identity" that unravel in the slightest breeze.
Perhaps a useful concept is the Hegelian take on "freedom"; that in any epoch freedom is defined by the will to overcome the obstacles one faces. There is no firmer definition of it than "intent".
A better modern word might be "lifestance" [0], a word I learned from hanging around with Rationalist/Humanist thinkers.
And here's what I think is a beautiful lifestance quote;
""" Act as though you are free, you might get lucky. You might be
free, who knows! Act that way it's worth trying! -- Rick
Roderick """