The Work of the Holy Ghost !
It is the Holy Spirit's job unto the Elect of God, those Christ died for, to save them from their sins, it is His mission to teach them about sin Jn 16:8-9
8And when he is come, he will reprove the world of sin, and of righteousness, and of judgment:
9Of sin, because they believe not on me;
Jn 6:45
45It is written in the prophets, And they shall be all[The Children] taught of God. Every man therefore that hath heard, and hath learned of the Father, cometh unto me.
By Nature we know nothing about sin, how terrible it is, and how deep it is. Oh yes, by nature we know about good morals, morality, we know its wrong to steal, become a drunkard, and commit murder, but sins of pride, self righteousness and covetousness we are ignorant of by nature. Look at Jn 3:19-21
19And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil.
20For every one that doeth evil hateth the light, neither cometh to the light, lest his deeds should be reproved.
21But he that doeth truth cometh to the light, that his deeds may be made manifest, that they are wrought in God.
You know what deeds are spoken of here as being evil ? Its the religious deeds of the nation ! Its the jews trying to make themselves right with God by the deeds of the Law. Rom 10:3
3For they being ignorant of God's righteousness, and going about to establish their own righteousness, have not submitted themselves unto the righteousness of God.
Being caught up into False Religion, no matter how sincere, that is evil deeds. When Paul spoke of those things in Phil 3:5-6
5Circumcised the eighth day, of the stock of Israel, of the tribe of Benjamin, an Hebrew of the Hebrews; as touching the law, a Pharisee;
6Concerning zeal, persecuting the church; touching the righteousness which is in the law, blameless.
Those things were his evil deeds spoken of in Jn 3:19
Now the only thing that can expose these things as evil, is the Work of the Holy Spirit. Jn 16:8
8And when he is come, he will reprove the world of sin, and of righteousness, and of judgment:
That word reprove is the same word in Jn 3:20
20For every one that doeth evil hateth the light, neither cometh to the light, lest his deeds should be reproved.
I understand this to mean, no man can come to the light unless their religious sinful deeds are reproved by a work of the Holy Spirit.
You see, it does not take a work of the Spirit to convince the natural man that stealing is an evil deed, or fornication and hate is a evil deed, but tell a man that his sincere effort to serve and please God without Christ is evil deeds, then you will see how difficult a task that is.
But, when God the Holy Spirit implants New Life from Christ in a sinner, with an application of God's Law, that sinner is effectually taught his sinfulness, in its deep spirituality, but also this sinner will be taught the Gospel of their Salvation !
Each elect vessel of Mercy will be Taught their sinfulness before God, even if its sincere false religion, and each one will come to Christ, that is Believe on Him. 2
