Boy, when you read those words it almost seems like the author of Hebrews was writing for the church today, or perhaps it is just that there are no new sins and errors.
We live in an era when we are not permitted to call evil what it is. We hear lots of chatter about "radical grace" and "nuance" but stuff like "sin" and "judgement" and "wrath" are out of bounds. What makes this so weird is that we are, supposedly, a people of the Book. We don't worship the Book, we don't idolize the Book but everything of a critical nature we know about the God we worship is found in that Book. That very book where we read about forgiveness and loving our enemies is also the same book where we are continually told to be on guard against error and evil.
My old wrestling coach when I was in middle school used to say "Practice doesn't make perfect, perfect practice makes perfect". In other words if you practice a lot but practice the wrong way, you don't get any better and probably get worse. The church today, and for a long time, has been doing very little practice when it comes to distinguishing between good and evil to the point that we find ourselves where we are today with many "Christians" not only failing to distinguish but in fact calling what God has declared evil to be good or at least not all that bad. What little practice we do when it comes to distinguishing good from evil seems to be flawed at best.
We of course can get overzealous in our practice. I have more to say on the semi-professional watchbloggers who can't wait to write someone out of the Kingdom over doctrinal infractions, real and imagine. Even so, the misbehavior of some ought not discourage the rest of the church from being on watch for evil, just as the failure of the church to speak strongly enough against divorce doesn't negate our principled stand again "gay marriage".
Something interesting to consider here is that maturity, something the church is all supposed to be striving for, is directly tied here to being able to rightly distinguish between good and evil. Instead of shouting down those who are sounding a warning against evil, sin, love of the world, etc., perhaps we ought to be standing beside them, with the Scriptures open?
The corrective to those who are overzealous in distinguishing good from evil is not to stop distinguishing at all but to be even more zealous in our study of the revealed Word. If we all desire to progress in maturity we cannot turn a blind eye to evil.