How does persecution help the church and spread the gospel?
Sifting the Church
Persecution separates the wheat from the chaff. When both sprout, they look very much alike, but when the winds, the rain, the sun, and the drought come out, only one will produce wheat, and it’s not the cheat. The winds of resistance begin to blow the chaff away and only the wheat remains. Sometimes, it is persecution that separates the saints from the “aint’s.” Obedience to God’s Word is generally a sign of conversion, but when no good works appear, then that person’s faith can be called into question (James 2). Ongoing sexual immorality will get some people dis-fellowshipped, as those who practice those things are not headed to the kingdom (Gal 5:21), so if a person professes faith in Christ, it doesn’t mean they possess faith in Christ.
Many talking about going to heaven won’t get there (Matt 7:21-23). Persecution sifts the church like a cook sifts wheat, removing all impurities from the batch, so with that thought in mind, Jesus spoke about the one who “was sown on rocky ground, this is the one who hears the word and immediately receives it with joy, yet he has no root in himself, but endures for a while, and when tribulation or persecution arises on account of the word, immediately he falls away” (Matt 13:20-21). Persecution sifts the false converts. Most people will die for the truth…but those who truly don’t believe Jesus is the Way, the Truth, and the Life (John 14:6), will quickly fall away when persecution starts ramping up.
Revivals or Riots
It seems everywhere the Apostle Paul went there was either a riot or revival. He always seemed to bring controversy, because the Gospel is radical compared to the world’s religions, and especially to the Jews. They could not accept a Messiah or Christ that would die on a cross. They thought this would be the last thing that would happen to Messiah, so they rejected Christ…and they rejected Paul’s teaching, following him and harassing him all the way to Rome. When they attempted to destroy the church in Jerusalem; when a great persecution arose (Acts 8), it was like trying to put out a grass fire. They kept stomping on it, but that only served to spread it, so in this sense, persecution helped grow the church and spread the gospel. So exactly how did persecution spread the church? Luke the Physician writes in the Book of Acts that “there arose on that day a great persecution against the church in Jerusalem, and they were all scattered throughout the regions of Judea and Samaria, except the apostles” (Acts 8:1). They were scattered in every direction. They might have left leave family, home, and work behind, but they took the gospel with them. Tertullian wrote, “the blood of the martyrs is the seed of the Church” (Apologeticus, Chapter 50), and indeed, much blood was spilt, but it caused the church to grow rapidly.
Tests our Faith
Not only does persecution remove a lot of false converts from the church, thereby purifying the Brid of Christ, but it also works to purify believers. It tests our faith. It tests our resolve. Will we wash out at the first persecutions? What about when family, friends, and co-workers start to harass us for our faith in Christ? I thing I know, persecution makes you either run or it makes you stand your ground. Every believer must realize they are swimming upstream against a downstream culture, but any old dead fish can float downstream. It is those who strive to enter the kingdom by repenting and believing in Christ, but even here, grace is a free gift of God (Eph 2:8-90), and so is the ability to repent (Acts 5:31, 11:18; 2 Tim 2:24-26).
Blessed by Persecution
When we are persecuted, our natural reaction is to pray for it to go way, but wait! The Apostle Peter says we ought to “rejoice insofar as you share Christ’s sufferings, that you may also rejoice and be glad when his glory is revealed” (1st Pet 4:13). Have you been insulted for your faith? I have, but “If you are insulted for the name of Christ, you are blessed, because the Spirit of glory and of God rests upon you” (1st Pet 4:14). Don’t you want that? Does it bring joy to think that the “Spirit of glory and of God rests upon you?” I would think so. Jesus knew great persecution was coming, and would get even worse after He ascended to the Father. Steven the Deacon said, “Which of the prophets did your fathers not persecute? And they killed those who announced beforehand the coming of the Righteous One, whom you have now betrayed and murdered, you who received the law as delivered by angels and did not keep it” (Acts 7:52-53). His point may have been, “You’re in great company. They did the same thing to those who represented God in the past.” You must be sharing and showing your faith if you’re being persecuted, but if you’ve never once been persecuted, maybe it’s time to examine yourself to see if you in the faith or not (2 Cor 13:5, 2 Pet 1:10-11).
Want more on how to be blessed by God? Jesus said, “If you were of the world, the world would love you as its own; but because you are not of the world, but I chose you out of the world, therefore the world hates you” (John 15:19). Wouldn’t you rather be loved by God than loved by the world? It sounds worse to save we’ll be loved by the world but not by God. I don’t want that, and I bet you don’t either, so just prepare for it, and know that you’re not alone. More and greater persecution is coming, and it will get worse and worse, up until the time Jesus’ arrives. In fact, “all who desire to live a godly life in Christ Jesus will be persecuted” (2nd Tim 3:12), but “Blessed are you when others revile you and persecute you and utter all kinds of evil against you falsely on my account” (Matt 5:11). When people insult me or use derogatory remarks, I simply accept that as a blessing, but if someone insults you because you trust in Jesus, here’s what your (and my) response should be: “Rejoice and be glad, for your reward is great in heaven, for so they persecuted the prophets who were before you” (Matt 5:11).
Here is some related reading for you: How to Respond to Persecution Jesus’ Way 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible: English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.