In another thread, Orthodox wrote:
"It may be an unfair exaggeration to say there are 30,000 unique denominations, as is sometimes quoted. Still, there ARE thousands, which is considerably more than 1 that existed a thousand years ago."
I don't know whether Orthodox intended his comment to apply to one thousand years ago and no other timeframe. If so, then the objection doesn't seem to have much significance. If there were other denominations before and after one thousand years ago, then what would be the significance of singling out one short period around 1000 A.D.? Even during that short period, there were many different groups professing to be Christian, with a wide variety of beliefs. He goes on to write:
"Just the other day I was talking to someone from a major protestant group in the Phillipines, who among other wierdnesses, only partakes communion once per year."
I'll assume, for the sake of discussion, that the group in question actually is Protestant rather than being labeled as such just because it isn't Roman Catholic or Eastern Orthodox, for example. I disagree with only partaking of communion once a year, but that difference among Protestants isn't as significant as many of the differences that existed among professing Christians prior to the Reformation.
Pre-Reformation Christians disagreed with each other on many issues, to differing degrees of significance. People may choose not to apply the term "denomination" to these pre-Reformation divisions, but many of these people acted independently of one another and considered their churches governmentally independent of other churches they disagreed with. As early as the second century, the pagan critic Celsus would comment:
"Christians at first were few in number, and held the same opinions; but when they grew to be a great multitude, they were divided and separated, each wishing to have his own individual party: for this was their object from the beginning....being thus separated through their numbers, they confute one another, still having, so to speak, one name in common, if indeed they still retain it. And this is the only thing which they are yet ashamed to abandon, while other matters are determined in different ways by the various sects." (cited in Origen's Against Celsus, 3:10, 3:12)
It's to be expected that there will be a wider variety of professing Christians with the passing of time and with the expansion of social factors like the sort of political freedoms we have today in places like the United States. Just as there's a wider variety of professing Christians today than 500 years ago, we can expect there to be a wider variety 500 years from now than today. The same could be said of atheists, Muslims, etc.
Through the centuries, we find many disputes among the churches that existed, one bishop writing against another bishop, one church avoiding fellowship with another, councils held in opposition to each other, etc. (see, for example, Hippolytus, The Refutation Of All Heresies, 9:2; Athanasius, Festal Letter 29; John Chrysostom, Correspondence Of St. Chrysostom With The Bishop Of Rome, Letter 1:4; Jerome, Letter 16:2; etc.) A figure like Cyprian comes to mind, who held a high view of the unity of the bishops and church unity in general, yet repeatedly asserted the governmental independence of each bishop and had multiple public partings with the bishop of Rome. People often advocated high ideals with regard to church unity, yet also added many qualifiers to those ideals and were willing to assert independence from other churches and oppose those other churches when disagreements arose. We can't just quote what these people said about unity while ignoring the qualifiers they added and the incidents in which they practiced disunity.
Even in the Middle Ages, when there tended to be more of an effort toward outward displays of organizational unity and assistance in such efforts from the state, we still come across many incidents like this one Philip Schaff described:
"Henceforward the Immaculate Conception became an apple of discord between rival schools of Thomists and Scotists, and the rival orders of the Dominicans and Franciscans. They charged each other with heresy, and even with mortal sin for holding the one view or the other. Visions, marvelous fictions, weeping pictures of Mary, and letters from heaven were called in to help the argument for or against a fact which no human being, not even Mary herself, can know without a divine revelation. Four Dominicans, who were discovered in a pious fraud against the Franciscan doctrine, were burned, by order of a papal court, in Berne, on the eve of the Reformation. The Swedish prophetess, St. Birgitte, was assured in a vision by the Mother of God that she was conceived without original sin; while St. Catherine of Siena prophesied for the Dominicans that Mary was sanctified in the third hour after her conception." (The Creeds Of Christendom [Grand Rapids: Baker Books, 1998], Vol. I, pp. 123-124)
People who belong to the same denomination often disagree with each other about matters more significant than how often they take communion. Two Baptists who belong to governmentally independent churches often have more unity with each other than two Roman Catholics have with one another.
"For even as the Lord who dwells in us is one and the same, He everywhere joins and couples His own people in the bond of unity, whence their sound has gone out into the whole earth, who are sent by the Lord swiftly running in the spirit of unity; as, on the other hand, it is of no advantage that some are very near and joined together bodily, if in spirit and mind they differ, since souls cannot at all be united which divide themselves from God's unity." (Firmilian, Cyprian's Letter 74:3)