What is a Sinner?
sinner : in ordinary speech, it means someone who is deeply depraved, evil, bad. However, that's not what the Christian faith means by the word. In Christian belief, 'sinner' is not a moral description, but a relational one. Sin is the broken state of our relationship with God. There's a distance, a gap between us (with the rest of the created universe) and God, a distance far too wide for us to cross over, a distance bridged only by God's act of coming over onto our side of the gap through Jesus Christ (God-with-us) and the Spirit that Jesus sent in His place. The nicest, kindest, most spiritual, and most virtuous of us is a sinner. The vilest, darthest, crookedest, most evil of us is a sinner. Everyone in between is a sinner. Each and all of these sinners are loved by God.
Perhaps it would be best to use a word which lacks the moralistic overtone of 'sinner'. That overtone undercuts the Christian message of grace for those on our human side of the divide. I would love to look at the good and pretend the bad away, it's so much happier -- but it is unreal. The words often put forward to replace 'sin' and 'sinner' fail to catch enough of the negative quality of that divide: it is very very bad for you (in fact, fatal) and is far from what God wants for you. Because the broken relationship is so bad for us, it has profound and deep effects on all of us and all we do. It is a part of our human identity and character (that which makes each of us who/what we are), whether we want it to be or not.
The Bible's Words for Sin
The Bible has all sorts of words to describe sin. The most striking of these is Heb. mešubah (infidelity); the covenant people Israel was chasing after other lovers, as the prophets described it. In the Hebrew Scriptures, other words include ‘ahar (transgression, law-breaking), ma’al (trespass), ‘awon (straying, wandering), tum’ah (becoming unclean), beged (disloyalty, treason), and peša (revolt, rebellion). The image of sin which the New Testament most picked up on was the idea of an archer missing his mark (Heb. ḥatta’t, Gk hamartia). Anyone who does these is in some sense a 'sinner'. The origin of hamartia is the reward from competition; due to missing the mark badly or often, the archer has no (ha-) share in the allotment (mer-) or prize.
Notice that these are word-pictures, metaphors that help to describe something that has so many angles that no mere word or even phrase can quite hit the mark. You can picture someone straying from the path into the dangers of the woods, getting lost. Or, you can picture armed brigands trying to establish control of your area by force. Or being soaked through and through with pig-mud. Some of these are relational, others personal, or ritual, or societal. But these are not the words the Bible uses for mere "mistakes". Christ did not die and rise to forgive mere "goof-ups". We go off-course because we deceive ourselves or willfully allow ourselves to be deceived by others. Sin is so pervasive, it colors everything we do. We all do these things, in all sorts of ways, thus we are all sinners. It took Jesus' death, the indirect and direct result of our being sinners, to clear this up and clean it out.
You can look up the dictionary meaning of 'sinner', without actually sinning.
If you're looking for forgiveness, go to Jesus.
What Does 'Iniquity' Mean?
iniquity [from Latin iniquitas, from inequus unfair, from in- (un-) + aequus (even, level); akin to Mod English equal]
- a state of malicious unfairness, inequality, injustice or unrighteousness.
- [less commonly] an act of malicious injustice; sin
Its word-field includes wrong(doing), crookedness, and transgression, not leveling with someone, not being 'on the level' with someone. It was often used to translate New Testament Gk adikia, which is injustice as to the law or judges. In Greek translations of Hebrew texts, it was often used to translate Heb. ’awon (bent; stray). Both words are about an action's character rather than the act itself; its sinfulness rather than the sin, its injustice rather than the crime.
The core meaning of Eng. 'iniquity' is 'unfair' or 'unjust', but it carries a deeper, more menacing connotation. The word, in older English, usually indicated malice from a depraved or evil or thoroughly selfish state of mind, which is what leads to being unjust. This is not quite the same as the Hebrew or Greek intent, but it developed in Latin and English under their influence.
I said, 'older English', because 'iniquity' fell out of common use more than a century ago, and when it is used, it is treated merely as a synonym for 'sin'. Bible translators have only recently begun to catch up with the change. Iniquity's a perfectly good word to use when you run out of more common ways to describe what it describes, but otherwise it's best to avoid using it outside of literary contexts, unless you just want to sound high and mighty. I would love to see its return in public discussion, regarding the sin of economic injustice and extreme disparity, but until that sort of recovery of the word comes to the general public, the word just sets up a barrier.
Lead me not into temptation.
I can find it entirely on my own.
What Is Original Sin ?
Original sin is not about infants having dreams of evil. It's not about how creative we are at sinning. (While there do seem to be a few geniuses at it, our sin is pretty much a variation of what's been done before.) And it's not about turning us into a miserable pack of whiny sad sacks moaning, 'Woe is me'. Original sin refers to the start and root of the brokenness of the human relationship with God. Because of original sin, even the best of us turn away from God in some way (theologians used to call this fact 'depravity'). Even the best of us at our best is in the same basic dilemma as the worst of us, and even the holiest of us at their tippy-top is a universe distant from God's holiness. No one is born with faith; it is poured into you by the Spirit as you live. Original sin and depravity do not mean we're basically all evil monsters (God originally created us good, says Genesis). Instead, it means there's some 'monstrousness' in all of us, and it affects everything we do. And, there's a bit of this monstrousness in whatever way we gather together -- clubs, teams, parties, unions, companies, cartels, ethnic groups, nations, governments, and churches. We each add a bit of our own monstrousness to the group, and we take into ourselves a part of the group's monstrousness. (We also add and take on goodness.) Our monster isn't something we created recently. It is rooted in our origins, in the very beginning of the human race, hence, it is 'origin-al'. But each of us gives it another twist.
What Is a Transgression?
transgression [ < Latin transgredi, past tense transgress- (to step or pass across) < trans- (across, through, beyond) + gradi (to go, walk, step)] to step over the line, to go past the boundary limits of the law, duty, or moral principle.
In common-talk, transgression has come to mean the same thing as 'sin', though the words point to very different things. To visualize 'sin', picture an archer with careless aim, who not only misses the target, but hits a person in the process; or, someone who chooses to aim at the person instead of the legitimate target. To picture 'transgression', think of someone who chooses to walk into someone else's property, despite the signs warning of danger.
Also in common-talk, it is used for acts that cross against social or cultural bounds, or against a public sense of the profane, though it is best reserved for more serious matters. In culture, crossing the bounds is usually a good thing, because it widens our range of thought and practice. It can become bad, though, when the social bounds are put there to keep us from having social warfare, which can quickly turn hateful and bloody. Even then, line-crossing may be necessary, but in most such situations it's best to find other ways to cross that particular line.
You can also check the dictionary definition of 'transgression'.