I find most Christians follow some vague/ambiguous definition of sin instead of referring to God’s definitions given in His word. Unfortunately many professing Christians then fail to grasp that Jesus set us free from sin (John 8:36) simply because they do not understand what “sin” is.
I’ll offer a concise explanation below.
God’s definitions of sin are basically covered by the following examples:
1: Mark 3:29 Blasphemy of the Holy Spirit. This sin will not be forgiven. Christians do not commit this sin.
2: John 16:9 Unbelief in Jesus. This is the sin the world is convicted of. Christians do not commit this sin either.
3: 1 John 5:17 “all unrighteousness is sin”. Christians are righteous in Christ so here we do not sin.
4: 1 John 3:4 “Sin is transgression of the law”. This is breaking the old covenant commandments resulting in a death penalty for transgression.
Christians cannot be accused of sin here as we are not under the law of sin and death. The law of the Spirit of life in Christ Jesus SETS FREE from the law of sin and death (Romans 8:2).
Regarding the law of sin and death it should be noted that “whatever the law says it says to those who are UNDER IT” (Romans 3:19,20).
And “the law was NOT MADE for a righteous person (Christians), but for…the ungodly and for sinners” (1 Timothy 1:9).
Also, “where there is NO LAW there is NO TRANSGRESSION (SIN)” (Romans 4:15).
We know sin was dealt with once and for all on the cross.
And “Our old man is crucified with Christ, that the body of sin might be destroyed” Romans 6:6.
Hence we see in 1Peter 4:1 “Therefore, since Christ suffered (crucified) for us in the flesh, arm yourselves also with the same mind (our old man crucified with him, Romans 6:6), for he who has suffered in the flesh (Romans 6:6) has CEASED from sin,”
Of course we still see Christians doing wrong (erroneously referred to as sin under man’s ambiguous definitions), but as sons of God we are chastised for our wrong.
Romans 6:2 asks “HOW shall we that are dead to sin, live in it any longer?”
1 John 3:9 answers this question. “Whoever has been born of God DOES NOT SIN, for His seed remains in him; and he CANNOT sin, because he has been born of God”.
Also see 1 Peter 4:18 “If the righteous scarcely be saved, where shall the ungodly and sinner appear”.
Clearly there are 2 different groups described here.
Group 1: Righteous (and saved)
Group 2: Ungodly/Sinner (unsaved)
Either we are righteous (in Christ) OR we are sinners. We can’t be both.