The one thing that I noticed about this post is your frequent use of two words, unskillful (19 times) and skillful (24 times). You seem to be using these terms in an unconventional way, a specialistic way. Once you use the word 'unskillful' in a quote from Thanissaro Bhikku, and from that I conclude that it is a Buddhistic way of talking about something else. I am not familiar with Buddhist literature.
How does one know what is skillful and what is unskillful behavior? How does one determined who is skilled and who is unskilled? Where does skill come from? And finally, are we born unskilled and, if so, how do we acquire it?
To contrast your use of "unskillful" with what I take it to mean, I offer this verse from Psalm 51:5 replacing the original words with the terms you use…
Behold, I was brought forth in unskillfulness,
and unskillfully my mother conceived me.
All that I can gather from your post, brother, can be summed up in this single observation: Until you recognize "unskillfulness" for what it really is, and what its effects are, you are just spinning your wheels.
I'd like to a make a couple of points in response. To begin with, I think that it may be a mistake to compare the Buddhist concept of unskillfulness to the Christian idea of sin unless we limit the idea of sin to the Greek word hamartia, which is closely related to the verb hamartanein or 'missing the mark.' As such, I'm not sure the use of 'unskillfulness' in place of 'sin' in Psalm 51:5 is entirely appropriate, if at all.
In the context of actions (kamma), the Pali term kusala, often translated as 'skillful' or 'wholesome,' basically means that which is not conducive to harm and pain, but to benefit and pleasure (AN 2.19). It denotes doing something well, such as in the case of playing a lute (see AN 6.55). The Pali term akusala (composed of the negative prefix a- + kusala), often translated as 'unskillful' or 'unwholesome,' basically means the opposite, or that which is not conducive to benefit and pleasure, but to harm and pain.
Actions are deemed unskillful if they lead to to self-affliction, to the affliction of others or to both. Conversely, action are deemed skillful if they don't lead to self-affliction, to the affliction of others or to both (MN 61). In this sense, Buddhist ethics and philosophy are basically empirical and pragmatic in nature, and these are descriptive labels that are limited to observable qualities and experiences (adjectives), not self-existent entities (nouns). The focus is on actions and their consequences.
At the heart of the practice, Buddhism encourages one to renounce their unskillful habits and desires, and to renounce what's conducive to short-term welfare and happiness in favour of what's conducive to long-term welfare and happiness. In the ultimate sense, this involves, to adopt an image from Plato's Republic, turning the soul (mind) away from the darkness of the visible realm (samsara) towards the light of the form of the Good (nibbana). But at the beginning, it starts with learning to ask the right kinds of questions, such as, "Is what I intend to do here skillful or unskillful? Will it lead to well-being or harm?"
One comes to know what's skillful and unskillful via repeated reflection (MN 61), which is one of the reasons Buddhism is called a gradual path (MN 107). From the Buddhist perspective, until we achieve moral perfection (i.e., the ending of kamma and the elimination of the skillful/unskillful dichotomy altogether), we all have the potential do both skillful and unskillful things, and this is why the Buddha often stresses the importance of being as mindful of our actions and the intentions behind them as we can. As the Buddha notes, "all skillful qualities are rooted in heedfulness, converge in heedfulness, and heedfulness is reckoned the foremost among them" (AN 10.15).
Skill is something that comes from practice, through trial and error. Unskillfulness, on the other hand, doesn't really come from anywhere; it arises out of ignorance (avijja), specifically ignorance of the four noble truths, and ignorance is simply a lack of knowledge. (Incidentally, this is almost identical to the Stoic's belief that people act in ways that are harmful to themselves and others out of ignorance, i.e., if they understood the nature of happiness, of the mind itself, they would never willingly act against their own happiness or the happiness of others.) I think Thanissaro Bhikkhu sums this idea up well in his essay "Ignorance":
Avijja, the Pali word for ignorance, is the opposite of vijja, which means not only "knowledge" but also "skill" — as in the skills of a doctor or animal-trainer. So when the Buddha focuses on the ignorance that causes stress and suffering, saying that people suffer from not knowing the four noble truths, he's not simply saying that they lack information or direct knowledge of those truths. He's also saying that they lack skill in handling them. They suffer because they don't know what they're doing.
The four truths are (1) stress — which covers everything from the slightest tension to out-and-out agony; (2) the cause of stress; (3) the cessation of stress; and (4) the path of practice leading to the cessation of stress. When the Buddha first taught these truths, he also taught that his full Awakening came from knowing them on three levels: identifying them, knowing the skill appropriate to each, and knowing finally that he had fully mastered the skills.
Stress he identified with examples — such things as birth, aging, illness, and death; sorrow, distress, and despair — summarizing it as five clinging-aggregates: clinging to physical form; to feelings of pleasure, pain, and neither pleasure nor pain; to perception; to thought-constructs; and to sensory consciousness. The cause of stress he identified as three kinds of craving: craving for sensuality, craving to take on an identity in a world of experience, and craving for one's identity and world of experience to be destroyed. The cessation of stress he identified as renunciation of and release from those three kinds of craving. And the path to the cessation of stress he identified as right concentration together with seven supporting factors: right view, right resolve, right speech, right action, right livelihood, right effort, and right mindfulness.
I agree that, until we recognize unskillfulness for what it really is, and what its effects are, we're just spinning our wheels; although I doubt that everyone will agree about what that means.