“And I say also unto thee, that thou art Peter, and upon this rock I will build my church” (Matthew 16:18)
From the founding of the Church upon the first Pope, Saint Peter, until ~1500 years later at the time of the reformation, the Church of Christ was a single, unified body of believers.
Today, the while it remains true that the Church is a single visible body of believers, this truth is not as easily recognized without deeper study than what was previously required due to the sheer number of Christian denominations (33,000 and counting) each preaching a different “version” of “Christianity”. The investigator of Christianity is now faced with the ever conflicting teachings of the Baptists, Methodists, Presbyterians, Unitarians, Anglicans, the various non-denominational sects, and every denomination, sub-sect and variety one could dream of. It is an incredible thing to behold, when one realizes this confusion was introduced in a space of 500 years while the 1500 years preceding it witnessed a single, unified Church founded by Jesus Christ (but for a few schisms).
The confusion sowed by such division should not be minimized – it is a serious issue eating the very core of Christianity. Even shortly after the reformation, Martin Luther witnessed this unfortunate side effect caused by the revolution of the ‘reformers’ and lamented:
“There are almost as many sects and beliefs as there are heads; this one will not admit Baptism; that one rejects the Sacrament of the altar; another places another world between the present one and the day of judgment; some teach that Jesus Christ is not God. There is not an individual, however clownish he may be, who does not claim to be inspired by the Holy Ghost, and who does not put forth as prophecies his ravings and dreams.” - Martin Luther