Cyprian

Like Tertullian, Cyprian (~200 - 258 AD) lived in Carthage (modern Tunis) in North Africa.  He was not baptized as a Christian until the mid-240's AD, but was rapidly put into church leadership roles including bishop in 249 AD.  He was fairly wealthy from a career in the legal profession, and gave some of his wealth to the poor after his baptism.  He was martyred in 258 AD.

His writings deal with controversies in the church during his time in leadership.  He also wrote about the plague that ravaged Carthage during Emperor Valerian's reign, encouraging the Christian's to stay strong in their faith and to help the sick.

One controversy he was involved in was how to deal with believers who had renounced their faith and worshiped the emperor during times of persecution and then desired to return to the church later.  One camp refused to allow them back in the church, while the opposite camp accepted all of them without question.  Cyprian took a middle ground, one that the bishop of Rome agreed with.

Cyprian was also the first early church father who championed infant baptism.  He felt they should be baptized as early as possible. Under his influence, 66 bishops declared themselves in favour of infant baptism in 253 A.D. and within a generation it had become standard practice in the North African churches.

Cyprian based many of his arguments around the term "Catholic Church" meaning the central, authoritative, and traditional church organization that claimed descent from the Apostle Peter.  In his Treatise "On the Unity of the Church" Cyprian refers to Matthew 16:18 where Jesus tells Peter that "on this rock I will build my church" and concludes that the authority given to Peter rests only with the Catholic Church.  Anyone who disagrees with the church leaders is causing disunity and is not part of the true church.  As Broadbent states in The Pilgrim Church (p.34), Cyprian went as far as claiming, "He who is not in the Church of Christ is not a Christian."

The church had now begun to exclude any and all Christians who disagreed with the most powerful bishops on non-core doctrines.  (By "non-core" I mean any doctrines of faith not expressly addressed in the New Testament.)

This large-scale excommunication of Christian believers created new practical problems in the church that had never existed before.  If an excommunicated group baptized people in the name of Christ, are those converts really Christians?  If those converts later come to the Catholic Church and renounce whatever "heresies" that existed in that group, do they need to be baptized again?  Cyprian argued yes; other bishops argued no, but it was an issue that was not resolved in his lifetime.

For the first time in history, it was no longer enough to be baptized in the name of Christ;  Cyprian now taught that one needed to be baptized in the Catholic Church to be a true Christian.