Tertullian wrote it in the second century: the blood of the martyrs is the seed of the church. Two thousand years of history have proven him right.
Tertullian was an African Christian writing around AD 200, when the Roman Empire was still figuring out whether to ignore the Christians or kill them. He chose the line as a rebuke to Roman officials who thought executing believers would solve the Christian problem. "Plures efficimur, quoties metimur a vobis; semen est sanguis Christianorum" — "We multiply when you mow us down. The blood of the Christians is seed."
Two thousand years later, the math has held.
The Roman lab
Rome tried for two and a half centuries to extinguish the church. Under Nero in the sixties. Under Domitian in the nineties. Under Trajan, Marcus Aurelius, Decius, Valerian, Diocletian. Each empire-wide persecution worse than the last. Christians were burned, beheaded, fed to lions, sewn into animal skins and torn apart by dogs.
And the church grew. It grew because every public execution preached a sermon Rome could not refute. Pagans watched their slaves and their soldiers and their senators die singing — believing what they were dying for was true. Some of them, watching, started to believe it too. The soldier guarding the execution of one believer became the next convert.
By 313, when Constantine issued the Edict of Milan, an empire that had set out to kill the church found that more than ten percent of its population was Christian. Within seventy years, Christianity was the official religion of the very empire that had tried to wipe it out.
China, in our lifetime
Chairman Mao expelled all Christian missionaries from China in 1949. The church inside China was small — perhaps one million Protestant believers and three million Catholic. Mao was confident the church would die out within a generation.
His Cultural Revolution beginning in 1966 was specifically designed to finish what his expulsion of missionaries had started. Bibles burned. Churches converted to factories. Pastors imprisoned, tortured, executed. For two decades, no one in the West knew what was happening to the Chinese church. Most assumed it was over.
When the bamboo curtain cracked open in the 1980s, Western missionaries returned, expecting to find ruins. They found a church of perhaps fifty million people — possibly more. By some recent estimates, China today has between ninety and one hundred million Christians. The country that tried hardest to kill the church accidentally watered it.
Why this works
Persecution kills believers. It does not kill faith. In fact, it does something nothing else does: it strips the church of everything cultural, comfortable, and false, and leaves only the true thing — the actual gospel, the actual Christ, the actual cost of following Him. A church under persecution is forced to be the church. Many other things look like the church when nothing is at stake. None of them survive when something is.
And persecution preaches. The pagan watching the believer die is forced to ask: What does she know that I do not? What does she have that is worth more than her life? Sooner or later, some of them go looking for the answer.
Implication
We are not commanded to seek persecution. Jesus told the disciples, when persecuted in one city, to flee to the next. There is no glory in suffering for its own sake. But when persecution comes — and it will come, in some form, to every faithful generation — the believer's response is not panic. It is patient courage. The Lord who multiplied the church through Roman blood is multiplying it through Chinese, North Korean, Nigerian, and Iranian blood as we speak.
He has not changed. The principle has not changed. The seed is still the blood. The harvest is still on its way.