Before His death this Man Who was also God had instituted a certain rite and Mystery called the Eucharist. He took bread and wine and changed them into His Body and Blood. He ordered this rite to be continued. The central act of worship of the Christian Church was therefore a consecration of bread and wine by priests in the presence of the initiated and baptized Christian body of the locality. The bread and wine so consecrated were certainly called (universally) the Body of the Lord.
The faithful also certainly communicated, that is, eat the Bread and drank the Wine thus changed in the Mystery.
It was the central rite of the Church thus to take the Body of the Lord.
There was certainly at the head of each Christian community a bishop: regarded as directly the successor of the Apostles, the chief agent of the ritual and the guardian of doctrine.
The whole increasing body of local communities kept in touch through their bishops, held one doctrine and practiced what was substantially one ritual.
All that is plain history.
The numerical proportion of the Church in the city of Carthage, where Tertullian wrote, was certainly large enough for its general suppression to be impossible. One might argue from one of his phrases that it was a tenth of the population. Equally certainly did the unity of the Christian Church and its bishops teach the institution of the Eucharist, the Resurrection, the authority of the Apostles, and their power of tradition through the bishops. A very large number of converts were to be noted and (to go back to Tertullian) the majority of his time, by his testimony, were recruited by conversion, and were not born Christians.
Such is known to have been, in a very brief outline, the manner of the Catholic Church in these early years of the third century. Such was the undisputed manner of the Church, as a Christian or an inquiring pagan would have been acquainted with it in the years 160-200 and onwards.
I have purposely chosen this moment, because it is the moment in which Christian evidence first emerges upon any considerable scale. Many of the points I have set down are, of course, demonstrably anterior to the third century. I mean by “demonstrably” anterior, proved in earlier documentary testimony. That ritual and doctrine firmly fixed are long anterior to the time in which you find them rooted is obvious to common sense. But there are documents as well.
Thus, we have Justin Martyr. He was no less than sixty years older than Tertullian. He was as near to the Crucifixion as my generation is to the Reform Bill—and he gave us a full description of the Mass.