The truth is, the earliest Christians were a far cry and did not "develop" out of the Catholic Church, nor did all the earliest Christians become Roman Catholics.
There were many who opposed Catholocism, and they were persecuted mercilessly for it. The first pope wasn't a Christian at all, and those who believe that Christianity began and ended with the Catholic church are sadly mistaken. Not all were taken in, not all believed in the Church, and local churches held out against the Roman Catholics from then until now.
"Constantine I of the Roman Empire
The Emperor Constantine I was, like emperors before him, high priest of the Mithraic religion. However, he was also interested in creating unity for the sake of ease of governance, and to this end he involved himself in a dispute between Christian groups over Arianism, summoning the First Council of Nicaea; this Council produced the Nicene Creed.
Constantine mitigated some differences between orthodox Christianity and its main competitor, the official religion of Sol Invictus. For example, he moved the date of celebration of Jesus' birth to December 25th (since this was the celebration date for the birth of Mithras and Bacchus, and also the date of other winter solstice festivals such as Saturnalia). In addition, Constantine instituted use of the Chi-Rho symbol, representative of Christianity, also alleged by some scholars to have had use as an obeloi for "auspicious" thus serving both Christian and non-Christian purpose simultaneously.
Critics of the merger of church and state point to this shift of the beginning of the era of Constantinianism when Christianity and the will of God gradually came to be identified with the will of the ruling elite; and in some cases was little more than a religious justification for the exercise of power.
Popular legend holds that Constantine I was Christian; however, he never publicly recanted his position as high priest of Mithras Sol Invictus, and the only alleged occurrence of Constantine I converting was on his deathbed (as reported by later Church Fathers), which is impossible to verify. However, it was not that unusual for people in the fourth century to avoid fully converting to Christianity until quite late in life, because of the strong warnings against continuing in sin after having converted and the spiritual consequences thereof."
History of Christianity - Christianity Knowledge Base
My religion is not a "break off" of the Christian religion. It is a religion which descends from the teachings of Christ and has nothing to do with the CAtholic Church...and never has. We've been labeled a variety of things, and many catholics have left catholocism after being witnessed to by non-Catholic NT Christians.
But the very fact that nobody can really trace the Baptist religion other than to point out where they have stood against the Catholic church (and before that, against others who would kill them) in a variety of times and ways tells me it's not an offshoot. YOu can see it all the way back to Christ, but it doesn't exist as a single definitive "religion" because it is instead a collective of "local" churches...people who join together to worship as the NT directs us to, in defiance of whatever happens to be the en vogue religion of the time.