Once the believer experiences the sanctifying grace of God through the Spirit of Christ and belief of the truth they are forever separated and separate from this world. Therefore to be set apart by the word of Christ always means the world will hate the believer (John 17: 14.)

Why does the world hate those whom the Lord sanctifies in spirit and in truth? Verse one says "a great multitude both of the Jews and also of the Greeks believed." This is important information. The Greeks loved the wisdom of the world and never had the law of Moses while, while on the other hand, the Jews had the oracles of God. Yet, both Jew and Greek repented from the same thing. In other words, prior to God giving them faith to believe Christ, both Jew and Greek were in the same camp. In confessing Christ they declared that all who do not believe Christ are exactly alike no matter how hard they try to put a difference between themselves. It is Christ alone who sanctifies and is himself our Sanctification. Consider what Paul repented of and it may help us to understand what they repented of and why the unbelievers were angered.

I am taking the following from Philippians 3: 5-11.

• The Jews turned from putting any confidence in the fact that they were circumcised the 8th day; likewise the Gentiles turned from putting any confidence in any ceremony which their fathers might have performed on their behalf. Both declared to all that no ceremony--even that given by the Lord--can make a sinner accepted of God.
• The Jews turned from putting any confidence in their heritage; likewise the Greeks confessed that none of their earthly relations profited them before the Lord. Both declared that only the electing grace of God sanctifies those who are the children of God; they are not of this world even as Christ is not of this world.
• When the Jews turned from the vain confidence they had in their knowledge of being able to quote the law and the prophets they confessed that their knowledge was no better than the worldly wisdom which the Greeks repented of. Both declaring that sinners can not know God of themselves but must be taught of the Lord in spirit and in truth.
• When the Jews turned from putting any confidence in their former zeal wherein they rejected the Gentiles and likewise the Greeks turned from boasting in their zeal against the Jews, both declared that only Christ makes a sinner to differ and truly separates us from this world.
• When the Jews repented of placing confidence in their obedience to the law and, likewise, the Greeks who did not have the law were granted faith, they both confessed that it is neither circumcision which avails or uncircumcision, but a new creation.

These Jews and Greeks confessed that though they once exalted themselves over each other using these various religious forms, the reality was they were both the same--without Christ, having no hope and without God in the world. By the separating grace of God, they repented and believed on Christ. They counted all the things they once considered gain, as loss for Christ. That they might win Christ-that is, the only reward they were seeking was Christ. They confessed they wanted to be found of God in Christ, not having a righteousness of their own by their vain attempts at obeying the law, but the righteousness which is through the fidelity of Christ by faith in him. By repenting and believing on Christ they confessed that 2 Corinthians 5: 19: God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and hath committed unto us the word of reconciliation....21: For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him. They professed Galatians 6: 14: But God forbid that I should glory, save in the cross of our Lord Jesus Christ, by whom the world is crucified unto me, and I unto the world. 15: For in Christ Jesus neither circumcision availeth any thing, nor uncircumcision, but a new creature. 16: And as many as walk according to this rule, peace be on them, and mercy, and upon the Israel of God. This is what it is to be sanctified by the electing grace of God, by Christ Jesus through the Spirit of God and belief of the truth.

Therefore, the unbelieving Jews and Gentiles hated them because they were of this world. The only means they had to separate themselves from others was by using those very things which the believers renounced as dung. Therefore, the unbelieving Jews and the unbelieving Greeks hated those whom Christ had separated for his glory. This is always the result when the Lord sanctifies his people through the Spirit of faith. And because only Christ can sanctify, therefore the same means which it pleased the Lord to use to sanctify his people from the evil of this world in the beginning, is the means he is pleased to continue to use to keep them from the evil, the gospel of his sanctifying grace. Thus we read in verse 3: Long time therefore abode they speaking boldly in the Lord, which gave testimony unto the word of his grace, and granted signs and wonders to be done by their hands.