This week the church remembers St. Cyprian, Bishop of Carthage and Patron Saint of our Parish of St. Cyprian's, Lacombe, Alberta. His feast day is listed as September 13th in both the Book of Common Prayer and the Book of Alternative Services, but both Wikipedia and the Encyclopedia Britannica have the date of his death (martyrdom) as September 14th, 258 AD (or "CE" if you prefer). The latter goes on to say that Cyprian's day is celebrated in the Western and Eastern churches on September 16, and in Anglicanism, on September 26!
No matter! Let us remember him with reverence and respect for his service to God and the church -- which began late in his life.
He was by profession a lawyer of Berber descent who became a Christian in about 246 AD. By 248 he'd been elected Bishop of Carthage, and found himself in the midst of persecutions lead by the Roman Emperor Decius. He went into hiding, while many of the church's followers recanted their faith in hopes of saving their lives.
By 251 he was able to return to Carthage and in May of that year was restored as Bishop. He then found himself managing the controversy about reinstating Christians -- including other bishops -- who had 'lapsed' in order to escape persecution. Cyprian expressed his empathy for reinstating lapsed laity, but drew the line at doing so for bishops and clergy -- and this brought him into conflict with the Bishop of Rome (i.e., the Pope).
The controversy continued, and he found himself facing off with the Novatians, who held that NO forgiveness was possible for lapsed Christians. The Novatians had been in Africa during the years Cyprian was hiding. After his return, many of those baptized by the Novatians wanted to return to the church. The question arose: was their baptism by Novatian valid or not?
Cyprian convened no fewer than three Councils on this issue between the autumn of 255 and the spring of 256. In the end, it was agreed that there could be no baptism outside the church -- i.e., absent the Holy Spirit -- so those baptised by Novatian had to be re-baptized to rejoin the church as followers of Jesus, the Christ.
As all of this was going on, Valerian had become Emperor in Rome, and persecution of Christians had been renewed with vigour. Cyprian was arrested and at first subject to exile, but by 258 was brought back to Carthage, tried, convicted and executed.
Centuries later the arguments about baptism remain -- with the Latin West supporting 'one Lord, one faith, one baptism' and the Greek East being inclined to re-baptize lapsed Christians.
All of this history around Cyprian is sourced mainly from his letters and tracts, which are included in the third and fourth volumes of the Patrologia Latina, a collection of writings of the early church fathers.