James 1:23-24 Anyone who listens to the word but does not do what it says is like someone who looks at his face in a mirror and, after looking at himself, goes away and immediately forgets what he looks like.
Is knowing yourself essential? Maybe not. There are people who lack even the basic level of self awareness. Yet they appear to function, somehow.
Is knowing yourself recommended? Definitely!
It’s good to be in tune with your emotions. To know if you deep down resent someone. That way, the next time they ask you out, you can just say no instead of being forced to say yes just because you are a polite person.
In a way it’s about knowing your preference. If you didn’t know what kind of food you like, it’s hard to navigate a menu. And if you don’t know what makes you happy and what makes you sad, what your dreams are and what you secretly dread then it’d be pretty hard to navigate through life.
E.g. you could be with someone and continue to be with them just because you’ve been with them as long as you remember. But if you were in tune with your emotions and had self knowledge you might come to realise that you’ve grown bored of them much sooner. Then you could do something about it. Instead of wasting years in a dead end relationship without either breaking up or doing something to patch up the relationship.
Now, I’m not saying that knowing yourself is the same as loving yourself. When you get to know yourself there might be parts of yourself that you don’t like. Which are incongruent with how you see yourself, or your true self. In which case, self knowledge allows you to know which parts of you _you_ don’t like. So you can change it. Or come to terms with it. Whatever.