Marcellinus was born in Rome. He was elected Pope on 30 June, 296. It was during his time that the religious persecution of Emperor Diocletian reached its zenith. The churches and even the holy scriptures were destroyed. Many Christians were mercilessly executed. Rivers of blood flowed through the streets. His judges were sending Christians to the slaughterhouse without a conscience. But the Christian community faced these with equanimity. They also killed the Pope at a time when torture and persecution were rampant. Enemies set fire to all the papal history, books and other documents written by him.
Tradition has it that the Pope, who saw the severity of the persecution of Christians, at one point renounced his faith and quickly repented and atoned for his sins with his own blood. He ruled the church for eight years.