You said
"The Church of the year 100 was not the Roman Catholic Church we see today."
The church still is the catholic or Catholic Church of the year 100.
http://www.ewtn.com/faith/teachings/churb3.htm
Excerpt;
The Creed which we recite on Sundays and holy days speaks of one, holy, catholic and apostolic Church. As everybody knows, however, the Church referred to in this Creed is more commonly called just the Catholic Church. It is not, by the way, properly called the Roman Catholic Church, but simply the Catholic Church.
The term Roman Catholic is not used by the Church herself; it is a relatively modern term, and one, moreover, that is confined largely to the English language. The English-speaking bishops at the First Vatican Council in 1870, in fact, conducted a vigorous and successful campaign to insure that the term Roman Catholic was nowhere included in any of the Council's official documents about the Church herself, and the term was not included.
Similarly, nowhere in the 16 documents of the Second Vatican Council will you find the term Roman Catholic. Pope Paul VI signed all the documents of the Second Vatican Council as "I, Paul. Bishop of the Catholic Church." Simply that -- Catholic Church. There are references to the Roman curia, the Roman missal, the Roman rite, etc., but when the adjective Roman is applied to the Church herself, it refers to the Diocese of Rome!
Cardinals, for example, are called cardinals of the Holy Roman Church, but that designation means that when they are named to be cardinals they have thereby become honorary clergy of the Holy Father's home diocese, the Diocese of Rome. Each cardinal is given a titular church in Rome, and when the cardinals participate in the election of a new pope. they are participating in a process that in ancient times was carried out by the clergy of the Diocese of Rome.
Although the Diocese of Rome is central to the Catholic Church, this does not mean that the Roman rite, or, as is sometimes said, the Latin rite, is co-terminus with the Church as a whole; that would mean neglecting the Byzantine, Chaldean, Maronite or other Oriental rites which are all very much part of the Catholic Church today, as in the past.
In our day, much greater emphasis has been given to these "non-Roman" rites of the Catholic Church. The Second Vatican Council devoted a special document, Orientalium Ecclesiarum (Decree on Eastern Catholic Churches), to the Eastern rites which belong to the Catholic Church, and the new Catechism of the Catholic Church similarly gives considerable attention to the distinctive traditions and spirituality of these Eastern rites.
He didn't mean it the way you mean it, I suspect.
And no, the church of 100 was not quite the church of 900, or 1200, or 1500, or 2007...there would be dogmas defined, heresies to be dealt with, the heavy, heavy persecutions to come, and many things which would be worked out.
What we had then was: the Eucharist. The development of bishoprics the way we think of them, baptism. The Holy Spirit to guide us, and the ending of the era of the Apostles, and the rise of Christian gnosticism. The doctrine of the trinity was not yet clearly defined, the definition of Mary as Theotokos was not yet clearly defined, the Nicene creed was not yet formed.
But the Spirit was there to guide us.
You would have recognized that the Eucharist was the eucharist, though. But the words of the service, and certainly the texts used for scripture wouldn't be done in the same way, since the New Testament hadn't been codified yet.
Different, and the same.
"The church still is the catholic or Catholic Church of the year 100."
"The church" is still very much around, and the "Roman Catholic Church" of today is certainly part of it, as are all the churches in communion with Rome AND all the churches in communion with Constantinople, Moscow, Antioch, Jerusalem, Alexandria, etc.