People think the Four Cardinal Virtues are religious, but they're not. Plato first listed them in his Republic, and that was well over 2000 years ago, long before Christianity.
All four are interrelated, so if you don't have one you don't have any.
They are: Bravery, Prudence, Justice, and Self-Control.
Not only the Greeks but the Romans thought about these things. Cicero wrote this: "Virtue may be defined as a habit of mind in harmony with reason and the order of nature. It has four parts: wisdom (prudentiam), justice, courage, temperance."
They're also in the Bible. The deuterocanonical book "Wisdom of Solomon" reads, "She [Wisdom] teaches temperance, and prudence, and justice, and fortitude, which are such things as men can have nothing more profitable in life."
I repeat this: "nothing more profitable in life."
To illustrate the Four Cardinal Virtues, look at the opposites.
I know two women who will say anything that pops into their heads to both men and women. It's not bravery. It's recklessness.
Both are impulsive, which isn't surprising. That's why there exists the saying, "reckless and impulsive." What's the opposite of reckless and impulsive? Prudence and self-control.
You can make the argument that bravery is not quite the opposite of recklessness, but just a degree of it. The Greeks made the argument that too much bravery is recklessness. This is why all the virtues are interrelated.
One of the women I know is a coward. If she decides she is not interested in a guy, she'll just dump him without a word to him. Reckless, impulsive, and cowardly - the opposite of self-control, prudence and bravery. Not surprisingly, her life is a catastrophe. Not surprisingly, the lives of both women are a catastrophe.
One of them had her business go under because she wouldn't give the people what they ordered. That's what Justice is - giving people their due.
Of course, I've seen the same thing among men. One I know quite well is what the more ignorant in the Manosphere call an "Alpha" - wealthy, good-looking, lots of women.
He's not an "Alpha." He's a cad. He has spent his life laying women. He lied to them, cheated on them, manipulated them.
I found him to be cowardly, reckless and impulsive. So has his best friend. He has little self-control. In other words, he lacked all four of the Four Cardinal Virtues. And he has ruined his life. He once told me if he had to do it over, he would have been a high-school coach instead of a doctor.
The Four Cardinal Virtues are about having a happy, successful life, based on confidence and competence. They are good practical wisdom, which is the only kind of "wisdom" worth anything.
Incidentally, "virtue" means "the powers of Man" and "cardinal" means "hinge," because it's the hinge for a life of well-being.
Unfortunately the Four Cardinal Virtues aren't taught anymore, not in school, not in the home, not in the churches. It's almost as if none of them want people to develop critical thinking skills.