Persecution of Christians by the Romans facilitated the rapid growth and spread of Christianity.
In the first three centuries, there was a lot of persecution of the Christian Church by Roman authorities. This ended up having a significant historical effect in that many Christians fled far and wide in the old world and wherever they went they preached the gospel of Christ.
About 12 emperors of Rome in the period 30 t0 311AD went out of their way to persecute Christians, and it was in this periods that Christianity spread widest.