Is huge. At first glance we might think they are synonyms. Certainly sin is iniquity and iniquity is sin but they have specific differences.
Sin is used in the Bible in many ways and each use pertains to the context of the doctrine being taught. We really do need to understand the differences between the different words in the original language for sin. We also need to examine what God means by iniquity.
The general use of “sin” in the Old Testament refers to first, our sin nature that was a result of Adam’s sin. We are not responsible for being born with a sin nature, we are only responsible for rejecting the remedy for it…Jesus.
Then, once the law of God is broken, this is deliberate sin. It is a bi-product of being born with our sin nature. We are unable to keep God’s law, and it is written on our hearts, until we are spirit-born, saved. We have to come to Jesus for forgiveness and believe on Him. Sin then has no power over us. If we deliberately sin, it is because we choose to. If we trespass unaware, He will show us and give space and power to correct it.
In the New Testament, we see many words used for sin in the Greek, and each is very specific to the context and doctrine being taught. I have to say that these are easily grasped because they are common sense. If we know our Bibles, then these slight differences in meaning between the Greek words, make sense.
For example, one word refers to a sin of ignorance. Another word refers to a sin that is ongoing. Another word refers to a sin that is knowingly and willfully and continually choosing against the known will of God. This is the word used in 1 John when he teaches us that there is a sin unto death for the believer.
Iniquity is another thing. Iniquity seems to be referring to a choice by a believer to fail in morality, when they know to walk uprightly and should be walking uprightly. This sort of behavior in a believer is called “iniquity”. The definition of this word today is gross immorality…wickedness. A rebellious believer is capable of wickedness. David is an example. It just cannot be unrepented-of, and ongoing. If an iniquity is unrepented-of and ongoing, then it is the sin unto death potentially.
Now the interesting thing is that God says this all through the Bible and in many ways. It is why I see for sure that lukewarm believers in the last days will not be raptured but will go into wrath to be beheaded…killed. But then they are resurrected with the righteous and reign with Jesus for 1000 years. They seem to have different roles but saved and resurrected as well.
God says in Isaiah, speaking of Israel at the time but also referring to the last day when the wrath of the Lamb comes upon the unbelieving world, that they will not cease from their iniquity until they die. It is the same for the lukewarm at the end.
It is a serious thing to ponder if we are believers. Be holy as He is holy is our command. We must put away wickedness or we will not be raptured. There are so many believers today who dabble in sin and their iniquity will not cease until they die.
Jesus told us to die now while we live. Put away the evil deeds of the old man. Purify your hearts and be not double minded. I think it is soon. Pray you are counted worthy. It is the righteous who vanish when the last trumpet sounds. Believers who are still loving iniquity will have to die to stop it. “Surely this iniquity will not be purged from you till you die” (Isaiah 22:14).