You mention a single flaw that isn't a flaw at all, I'd have to know the full range of flaws you are talking about before I could agree or disagree. It appears you are really stating nothing new, sin is sin unless it is not sin, as in the one you mentioned.
For instance, living fornication as a lifestyle, I mean something we are always ready to do if the opportunity presents, is one very real thing that is not a flaw, that can end us up in Hell, and the type thing I am referring too.
Some say that is no problem, and it's covered by grace, or even go so far as to promote it by stating if we decline to do something like that, and teach it should not be done, we are legalistic, don't accept what Christ did for us and a number of other blah, blah, blah's to try to put a guilt trip on those who try to do good, or in the words of some, for doing such a terrible thing as trying to be proactive in our salvation. That is exactly how Satan, the master of confusion works.
There are those who will never buy Satan's junk, they know the truth and are happy to oblige God, where others don't like God's plane and want an easier one that lets them have their cake and eat it too, those are the ones that will be taken in/will allow it, and for that reason, it's no ones fault but their own.
Most of that is not directed at you, Gideon.
I fully understand your questioning this. Under the new covenant, we are told that whatsoever is not of fairh is sin. Before it was written rules, but now God has given us His Holy Spirit to rule (think 'umpire') in our hearts.
Let me give you an example. You are driving on te interstate with your family. Suddenly, a car zooms up behind you and stays about one foot from your rear bumper. You tap your brake to try to move him back to a safe distance. He then speeds around you, cuts quickly in front of you and slams on his brakes, with you narrowly missing him.
What is your reaction? Most likely you will get upset at his foolish and dangerous behavior. Even angry. Have you sinned? Nope. But now the temptation comes to react back and suddenly you feel the check of the Spirit to let it go. No way, you think. This fool needs to be taught a lesson.
Have you sinned now? Yup. One was a reaction. Another a willful choice. BIG difference.
As my issue was lust, let's use that as an example. You are driving along and see a shapely woman walking in heels down the street. Your eyes focus instinctively on her beauty. Sin? Nope. However, you suddenly are tempted to lust after her, to do more than admire. The Spirit checks you and you say Thank you Lord that I do not have to go there and that you can keep me from falling. Have you sinned? Not at all.
Our human weaknesses, areas that the fruits of the Spirit have not developed yet, are NOT sins. We still live in fleshly bodies but we are no longer of the flesh. We are told that as new creatures, we owe the flesh NOTHING. Oh, that we might believe that.
Willful sin is deadly. It puts us against the Holy Spirit, and if persisted in without repentance, hardened our hearts.
Slowly but surely, our faith becomes mental agreement but our heart, where faith is born, becoming so hardened, so calloused, that discovering the childlike faith again is difficult if not impossible. We are told that if our hearts dondemn us, God isgreater thsn our hearts and knows all things. The walk God has for us is not one of "I am just a crappy sinner saved by grace". No, our testimony is to be I WAS a terrible sinner, and by the grace of God, I am not only forgiven of it, but I am delivered from its grasp. That is what will get the attention of the lost seekers in the world. The first is simply our excuse to remain hypocrites, and they see right theough us. But when a man says that despite our terrible past, God has both forgiven us and set us free indeed, that is a man who has started walking as a true overcomer.
I hope this clarifies it a bit.
Blessings,
Gideon