In Psalm 32:5, the psalmist says, “I acknowledged my sin to you and did not cover up my iniquity. I said, ‘I will confess my transgressions to the LORD.’ ” In this one verse, “sin,” “iniquity,” and “transgression” are all mentioned. Basically, the three words communicate the same idea: evil and lawlessness, as defined by God (see 1 John 3:4). However, upon closer examination, each word also carries a slightly different meaning.
The word sin and its cognates are used 786 times in the New International Version of the Bible. Sin means “to miss the mark.” It can refer to doing something against God or against a person (Exodus 10:16), doing the opposite of what is right (Galatians 5:17), doing something that will have negative results (Proverbs 24:33–34), and failing to do something you know is right (James 4:17). In the Old Testament, God even instituted sacrifices for unintentional sins (Numbers 15:27). Sin is the general term for anything that “falls short of the glory of God” (Romans 3:23).
Sin leads to a downward progression that, without the restoring power of the Holy Spirit, we all tend toward. The sin nature is present in every human being born since the Fall of Adam (Genesis 3:6–7; Romans 5:12). If left unchecked, continual sin leads to a “reprobate mind,” spoken of in Romans 1:24. Our sin nature causes us to gravitate naturally toward selfishness, envy, and pride, even when we are trying to do good. The apostle Paul alluded to his propensity to sin when he wrote, “For I know that good itself does not dwell in me, that is, in my sinful nature. For I have the desire to do what is good, but I cannot carry it out.” (Romans 7:18).
The sin nature leads to trespassing. A trespasser is someone who crosses a line or climbs a fence that he should not cross or climb. A trespass may be intentional or unintentional. Trespass can also mean “to fall away after being close beside.” Peter trespassed when he denied Jesus (Luke 22:34, 56–62). We all “cross the line” in thought, word, or attitude many times a day and should be quick to forgive others who do the same (Matthew 6:15).
Transgression refers to presumptuous sin. It means “to choose to intentionally disobey; willful trespassing.” Samson intentionally broke his Nazirite vow by touching a dead lion (Numbers 6:1–5; Judges 14:8–9) and allowing his hair to be cut (Judges 16:17); in doing so he was committing a transgression. David was referring to this kind of sin when he wrote, “Blessed is the one whose transgressions are forgiven, whose sins are covered” (Psalm 32:1). When we knowingly run a stop sign, tell a lie, or blatantly disregard an authority, we are transgressing.
Iniquity is more deeply rooted. Iniquity means “premeditated choice, continuing without repentance.” David’s sin with Bathsheba that led to the killing of her husband, Uriah, was iniquity (2 Samuel 11:3–4; 2 Samuel 12:9). Micah 2:1 says, “Woe to those who plan iniquity, to those who plot evil on their beds! At morning’s light they carry it out because it is in their power to do it.” In David’s psalm of repentance, he cries out to God, saying, “Wash away all my iniquity and cleanse me from my sin” (Psalm 51:2).
God forgives iniquity, as He does any type of sin when we repent (Jeremiah 33:8; Hebrews 8:12). However, iniquity left unchecked leads to a state of willful sin with no fear of God. The build-up of unrepentant sin is sometimes pictured as a “cup of iniquity” being filled to the brim (Revelation 17:4; Genesis 15:16). This often applies to nations who have forsaken God completely. Continued iniquity leads to unnatural affections, which leads to a reprobate mind. Romans 1:28–32 outlines this digression in vivid detail. The sons of Eli are biblical examples of reprobates whom God judged for their iniquities (1 Samuel 3:13–14). Rather than repent, Eli’s sons continued in their abominations until repentance was no longer possible.
The biblical writers used different words to refer to sin in its many forms. However, regardless of how depraved a human heart may become, Jesus’ death on the cross was sufficient to cover all sin (John 1:29; Romans 5:18). Psalm 32:5, quoted at the beginning of this article, ends with these words: “And you forgave the guilt of my sin.” The only sin that God cannot forgive is the final rejection of the Holy Spirit’s drawing to repentance—the ultimate fruit of a reprobate mind (Matthew 12:32; Luke 12:10).
 Got Questions Ministries. (2010). Got Questions? Bible Questions Answered. Bellingham, WA: Logos Bible Software.