Can we be forgiven of things we don't presently know are sinful? In 1 John 1:9, we're told the following (NKJV, emphasis added):
If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
I've recently been listening to a debate on whether a Christian can be forgiven of sins of ignorance, things one doesn't presently know to be sinful. In the debate, three different interpretations of confessing sins are offered, with only two of the three being endorsed by either of the two debaters. I'll list them in order of how specific the confession must be.
To "confess our sins," we must name every instance of sin we ever committed. "On October 11th, I lied to my boss about why I was late to work." (Neither debater took this extreme position.)
We don't have to name off the time and date of every sin we ever committed, but we do need to confess "our sins" (not simply that we're sinful). Therefore, if we commit the sin of lying, then just praying, "Forgive me of my sins" is too general; we must ask forgiveness for lying specifically. "Father, forgive me for the times I've lied." This also implies we must know that lying is sinful, or else we won't know to confess it. If we don't know that lying is sinful, we must find out and then confess the sin of lying before we're forgiven.
If we make general confessions of sin (e.g., "Forgive me of my sins"), we are confessing sin. And if we confess any sin at all, 1 John 1:9 says we'll be cleansed from "all unrighteousness." Therefore, if we're guilty of things we don't yet know are sinful, they'll also be forgiven.
The three positions above hinge on what it means to "confess our sins," whether it's (1) listing off each and every specific sin we committed, (2) confessing each type of sin we committed, or (3) confessing that we've sinned in general.
Do other passages in Scripture that use the phrase "confess sins" ever involve (3) general confessions? Specifically, I'm looking for whether verses use the expression "confess sins" but involve general confessions, if such verses exist. For example, Nehemiah 1:6 might qualify since it says Nehemiah would "confess the sins of the children of Israel" (NKJV, emphasis added) but, I assume, did not involve listing each type of sin.
What does it mean to "confess our sins"? Does the expression "confess sins" ever involve (3) a general confession in Scripture? If so, where, and does it shed light on 1 John 1:9?
Note: My primary question is on what the phrase "confess ... sins" means in 1 John 1:9 and, to back up one's answer, verses elsewhere in Scripture where "confess sin" is used in that sense (hence my example of Nehemiah 1:6). This is a Hermeneutics site, so focus more on how the expression "confess sin" is used in Scripture rather than the general theology of forgiveness.