No, being horrible is not expected or accepted. The Puritans (read: Evangelicals) like to interpret it that way, and in fact they do that because it absolves them of personal responsibility. “Well, I don’t do that one really terrible thing, therefore I can feel secure and not worry about my behavior.”
In reality, sin just means error, imperfection. It’s an acknowledgement that no human can be perfect the way that God is perfect, no matter what. The correct response to this should be ongoing self-evaluation, humility, and caution against slipping into the many easy faults of humanity. We should all be repenting constantly because obviously we make mistakes all the time, and all we can do is keep trying to be better, do better. This is what you find in classical literature like Thomas Kempis’s The Imitation of Christ.
If you see someone (and I know this is common) running around claiming absolute security in their righteousness with God, then you’re seeing a person who is quite literally actively sinning.
The knock on effect of this whole situation is that Christians who don’t believe they know all and speak for God (another sin: taking the Lord’s name in vain) don’t get public attention because we don’t run around shouting at people about our religious beliefs.
It’s an acknowledgement that no human can be perfect the way that God is perfect, no matter what.
Does the scriptures speak towards why God is perfect, and why we’re imperfect?
Specifically, if we’re made in God’s image, then doesn’t that mean God is not perfect either, or that we were purposely made imperfectly?
Does the scriptures speak towards why God is perfect, and why we’re imperfect?
This is a close cousin to the problem of pain. Many smarter people than I have debated both around and around for centuries, and come no nearer an answer than when they started. The Bible gives us a how, and a who, but not a why. Honestly I wish there was more, but alas.
And who created this definition that you’re referencing? You speak as if it’s the authority on what is and isn’t Christian.