After the murder of Christ and His apostles, there were a couple of patterns that started to appear that should shape the way we see the period between that time and about 1820 A.D.
The first pattern is that of scriptural aggregation and organization that relied on orthodoxy rather than generating the orthodoxy. Scholar after scholar did their work to collect the writings and accounts of the apostles and Christ and one thread was constant, even amongst the more intellectually honest of them - the means by which writings were rejected or accepted relied heavily on how their teachings matched that of the popular viewpoints of the peoples of their time. This is not a slight or a secret - Eusebius and others were explicit about this methodology of observing trends to determine what to leave in or out of the Bible. One can note the problem with accepting scripture based on its relevance to popular opinions instead of shaping those opinions by the scriptures themselves.
The second pattern starts with tensions in theology arising, followed by attempts to quell those tensions with violence and dogma. When there were too many people to murder and exile or the tensions grew too great, theology would adapt and adjust, usually using the latest Greek philosophy to resolve the tensions. Because of the unbiblical nature of the pagan philosophies applied to scripture, tensions would inevitably re-emerge. This cycle would continue over and over - enforcing a dogma, killing/punishing dissenters, and adjusting the dogma when needed.
When these patterns emerge, one major question should be asked: If the authority existed on the earth to resolve these tensions, why did it take philosophy outside of Christianity and thousands of years and several creeds to try to do so, and why did it ultimately fail to contain the ever expanding number of factions within Christianity? The answers in support of any one particular assembly, despite that fracturing, are complicated and more numerous than the factions themselves, but the answer that favors an apostasy is simple: that authority was never there and was erased from the earth with the death of the last apostle.
The restoration of the gospel and authority on the earth wasn't necessary because the earth and the people on it needed another reformation - another attempt at orthodoxy by reconciling tradition and philosophy with personal interpretation - it was necessary precisely because that method and cycle wasn't producing what it had intended to: the true church of Christ on the earth.
The Aggregation of the New Testament
There were many bright scholars that attempted to put together the various writings that we now accept as the New Testament. Among them were: Irenaeus, Clement, Tertullian, Origen, Eusebius, and Athanasius. We also have a list known as The Muratorian Fragment (author unknown), and the ratification of scripts from the Council of Hippo. There is one catastrophic academic failure threaded through those scholars/lists that must be identified: every single one had selection criteria based on what was already popular. In other words, the orthodoxy generated the scriptures instead of the scriptures generating the orthodoxy.
Imagine you're trying to form an opinion about something and instead of deriving your emotions from the facts, you decided ahead of time what your emotions were going to be on the subject and then elected the facts that validated your chosen emotion. This is precisely the same mechanism that was used throughout to select or reject each writ of scripture. This selection method was likely not only used out of convenience, but out of social necessity, as the charge of heresy quickly became central to the theme of early Christian theology and never left it.
It's worth learning the phrase directly related to the threats of violence that came out of institutional authority aimed at anyone who would threaten that institution's thinking: The replacement of kerygma for dogma. Kerygma, being Greek for "proclamation" or "preaching", which is to say: the gospel - and dogma, from Greek, then Latin, meaning "opinion" or "philosophical tenet", which is taken now to mean authoritative doctrine. So the replacement of kerygma for dogma means to replace the gospel with authoritative decree. That replacement is central to the cycle of tension, violence, and adaptation explored next.
The Heresy Cycle
This cycle is so clear that it's hard to think about the history of Christianity without it. The tension that most are familiar with that started it all is the tension of the Godhead - who's in it, in what way, and by what means - in other words: "who exactly do we have to thank for our creation and redemption?". The early scriptures, including the old testament, paint a confusing picture - one where Christ is one with God, He also is God, but He's also completely separate and has a body. Explored in more detail in "The Trinity and the LDS Godhead" essay, there are many scriptures that indicate many ideas - that God is one Being, that Christ is God, that Christ is less than God, that Christ is one with God, etc. Without a prophet receiving revelation to clarify these scriptures, humanity was left to guess how they're reconciled and hope that the interpretation they arrive at is not only correct and justified by scripture, but justified by scripture that was selected as part of canon correctly. No wonder there were a lot of schisms and disagreements early on.
What this led to was leaders convening bishops to attempt to resolve the matter. What ultimately resulted from each of those conventions, however, was dogma, not kerygma - a decree about how you can talk about the Godhead rather than any useful positive assertion that would actually demystify It. The first and most popular convention produced the Nicene creed, where Arians latched on to John 14:28 when Christ declared the Father greater than Himself and Trinitarians latched on to another verse in that same gospel, John 10:30, where Christ states He and the Father are one. Surely there were many more scriptures in the theological battle at Nicaea, but those two readily sum up the issue.
Unfortunately for the orthodoxy, that convention did not resolve the dispute and between then (325 A.D.) and the next convention (381 A.D.), there were multiple charges of heresy backed up by violence, removal of property, and exile. Part of the problem for why the convention didn't resolve the issue is that it didn't resolve the tensions in the scriptures - it used Greek/pagan metaphysical terms and philosophy to encapsulate the tensions and ambiguity without resolving them and then created enforcement around the usage of those terms. The most notable term being "homoousious" - the term meant to describe how Christ, the Father, and the Holy Spirit can be distinct, yet one. The problem with that term is it just means "of the same substance" without any explanation for what that actually means. The other important philosophical concepts imposed upon Christianity in an attempt to relieve it of the tensions of its day were: Immutability (unchanging), Incorporeality (no body), Divine Simplicity (one entity/being), Timelessness, and a few others. These are all explicitly Greek philosophical notions incorporated into a tradition whose scriptures don't necessarily support any of them on a face reading.
The Bed is Made
Once Greek philosophy was injected into the orthodoxy, there was no removing it without completely undermining itself. The next convention produced the niceno-constantinopolitan creed in 381 A.D. This creed is particularly demonstrative of the replacement of kerygma for dogma by the nature of mandate surrounding the convention: The Roman Emperor who convened it, Theodosius I, made the result of that convention law prior to the convention even happening. Once again, like in the previous creed, more Greek philosophy was injected: ekporeuomenon - a Neoplatonic emanation concept describing how the Spirit derives from the Father was brought in among other concepts.
Without detailing a full history between Christ's resurrection and 1820 A.D., sufficeth to say that this pattern of orthodoxy adopting pagan, or Hellenistic (as it's more properly named) concepts to fill gaps while creating others continues over and over again. In computer science the common joke and maxim is that you can't fix a bug without introducing two more - this readily applies to the patchwork of philosophies applied to the orthodoxy in attempts to clean it up. To give you an idea of just how fundamental this pattern is to the development of Christianity over 1500 years, here is a list of leaders who tried to resolve theological tensions with Greek philosophy, creating new tensions in the process:
Pre-Nicene
- Origen (185-253 AD) - Neoplatonic synthesis, pre-existence of souls, allegorical scripture interpretation
- Justin Martyr (100-165 AD) - Logos Spermatikos, first major Greek philosophy import
Nicene Era
- Athanasius (296-373 AD) - homoousios, formalized Neoplatonic divine attributes
- Basil of Caesarea (330-379 AD) - Cappadocian theology of the Trinity, Greek philosophical vocabulary for the persons
- Gregory of Nyssa (335-395 AD) - deepened the Neoplatonic mystical tradition, apophatic theology
- Gregory of Nazianzus (329-390 AD) - Trinity as three relations rather than three beings, philosophical refinement of Nicaea
Post-Nicene / Augustine's Era
- Ambrose of Milan (340-397 AD) - brought Neoplatonic reading of scripture to the West, directly influenced Augustine
- Augustine (354-430 AD) - the dominant synthesis: Neoplatonic divine attributes, predestination, timelessness, analogical language
- Boethius (480-524 AD) - divine timelessness formalized, Aristotle's logic transmitted to the West
Dark Ages / Early Medieval
- Pseudo-Dionysius the Areopagite (5th-6th century AD) - most extreme apophatic theology, directly from Neoplatonism, enormously influential
- John Scotus Eriugena (810-877 AD) - translated Pseudo-Dionysius, comprehensive Neoplatonic-Christian synthesis, condemned twice
High Medieval - Pre-Scholastic
- Anselm of Canterbury (1033-1109 AD) - ontological argument, satisfaction theory of atonement, father of scholasticism
- Peter Abelard (1079-1142 AD) - dialectical method applied to theology, Sic et Non, condemned twice
- Bernard of Clairvaux (1090-1153 AD) - embedded Neoplatonic mystical inward turn into Catholic devotional theology
- Hugh of St. Victor (1096-1141 AD) - synthesis of mystical and rational traditions
- Peter Lombard (1096-1160 AD) - Sentences systematized all unresolved tensions, became standard theology textbook for 400 years
Aristotle Arrives - Late Medieval
- Averroes / Ibn Rushd (1126-1198 AD) - transmitted Aristotle back to Europe via Arabic commentary
- Albertus Magnus (1193-1280 AD) - first comprehensive Aristotle-Christian synthesis, Aquinas's teacher
- Thomas Aquinas (1225-1274 AD) - the definitive synthesis, five ways, analogical language, nature-grace, two layers of Greek philosophy fused
- Duns Scotus (1266-1308 AD) - challenged Aquinas's synthesis, voluntarism, univocity of being, created new tensions
- William of Ockham (1287-1347 AD) - nominalism, severed reason from faith entirely, dissolved Aquinas's synthesis, directly fed Luther's formation
The Threshold
- Jan Hus (1369-1415 AD) - sola scriptura before Luther, burned at Constance
- John Wycliffe (1320-1384 AD) - sola scriptura, bones exhumed and burned posthumously
- Meister Eckhart (1260-1328 AD) - pushed Neoplatonic apophatic theology to its logical conclusion, condemned posthumously
The Abstraction Problem
In computer science there's another important concept known as abstraction, which has a similar function and meaning in software as it does elsewhere - it means to wrap up more complicated code into some parent or wrapper code whose interface is much more intelligible or simple. It adds an extra level of indirection, turning something undesirable to manage into a black box you don't have to think about. With regards to abstraction there is a maxim known almost universally - taken both as a joke and a truth: The only problem abstraction can't solve is too much abstraction.
Why bring this up? Because that same idea applies nearly perfectly to the Greek philosophy problem that was building inside Christian orthodoxy for centuries, leading to the reformations in the 1500s: the only problem Greek philosophy couldn't (apparently) solve was too much Greek philosophy. After so many centuries of creed upon creed, paganism upon paganism, the tensions grew so great that theologians started taking note. Most notable, of course, is Martin Luther, who was disturbed not only by the scriptural tensions he saw in the catholic church, but the heavy application of Hellenism in their understanding. Had the catholics caught him, he most certainly would have been killed for his trouble in pointing out the overuse of that philosophy.
Less known than Luther, but still very central to the story, is Michael Servetus - who took the cleansing of Greek mysticism a step further and started applying it to the trinity itself. Unfortunately for him (and humanity), it was a step far enough to enrage not only the Catholics, but the reformers as well, and he was burned at the stake for his troubles by a fellow reformer, Calvin.
Before proceeding, it's important to point out that there's a definite hypocrisy in violating Christ's message of peace, mercy, long-suffering, and loving your enemy when employing violence to protect your interpretation of His message. This was particularly noted by Sebastian Castellio (1515–1563), who was a real hero of religious freedom and an underling of Calvin. Castellio made note of that hypocrisy and is also known for the statement that "To kill a man is not to protect a doctrine, it is to kill a man". Castellio's ideals were greatly appreciated by John Locke and somewhat directly contributed to the eventual first amendment of the United States of America, so enough praise can not be stated for his nobility and character.
The Clear Picture
So now the picture should be clear: The constant attempts at iteration with the ancient Greeks and enforcement of dogma led to the eventual reformation era. The problem that the reformation couldn't fix is the same problem Protestants and Catholics face today: individual interpretive ability leads to different outcomes. This has produced numerous schisms amongst Catholics and nearly 47,000 protestant denominations.
It should be somewhat clear based on this brief historical narrative alone that the power and authority to reveal the true nature of God and the true meaning and correctness of scripture has not been on the earth since the apostle, John, was taken from it. Since that time, man has struggled to maintain Christianity, often relying on decree and enforcement when the populace could not be convinced of the theology. Once man was free of the chains of theocracy, he too was free to think for himself and think he did. Man produced an immense number of diverse congregations and beliefs, largely relying on his own abilities to read scriptures. Some men removed more Hellenism, like the Unitarians, and some continued relying heavily upon it, like the Anglicans and Lutherans.
Inasmuch as man is left without the ability to receive direct revelation from heaven, he'll have no authority outside himself to determine the truth and thus he'll continue to struggle. This era, since the last of Christ's anointed and until 1820 A.D., when authoritative prophets were returned to the earth, is what one might call The Great Apostasy - and many people are still in it. This is why a restoration of Christ's church and apostolic, revelatory authority was and is so necessary and why a church like The Church of Jesus Christ of Latter-day Saints brings such significant hope and joy to the world. No longer must we fight amongst ourselves over doctrine and dogma, we can receive the answers directly from God - similar to virtually every era before ours.