Ehrman is one of the top biblical scholars (biblical historians?) and he tows pretty mainline, well-researched positions so I don't think his views are particularly controversial or should be treated as prima facie wrong. I think it's possible that his views are being misrepresented here.
Really? I am familiar with him largely through his name being synonymous with a sort of liberal "debunking" of the Scriptures. It certainly isn't a confirmed fact that any Gospel was written before any other. If Colossians wasn't written by Paul it still likely was written by someone very familiar with Paul around the time that the Gospels were written, and so represents one of the very earliest Christian voices calling Christ the entity through which all things are created and sustained (sounds a lot like God). I Peter is dated to the early 60s AD if Petrine authorship is accepted, and this puts Jesus being called Lord and prayers to Jesus in with the very earliest Christian texts in existence.
Attempts to deflate Jesus in the early church aren't unique to Ehrman of course and there has been a trend of them since the 1970s. The extreme end of this is "Jesus as a misunderstood social critic," which seems to have more to do with the desire to co-opt Jesus for contemporary political debates than anything in the Gospels, as Jesus does things in Mark like affirm he is the Christ and talk about coming down on a cloud with the Might One, etc.
The current academic system preferences novelty and creativity, which unfortunately leads to provocative theses gaining ground simply for being provocative. This isn't just true for Biblical studies. This is the driving factor behind Ionannodis' famous paper "Why Most Published Research Findings Are False." The drive to get citations and standout for tenure just make this worse, and it effects a wide array of fields (e.g., there has been a lot of work on this incentive structure in economics)
The most true thing you could say about the church prior to the late third century is that it seems like it was quite diverse and no one really knows the order in which major texts were composed or who wrote them or why different editorial decisions were made. But this is obviously uninteresting and so you get all sorts of theories and supposition that rise and fall in popularity despite the underlying evidence staying the same.
Being mainstream doesn't mean "being supported by good evidence," in this area. From the late 1800s to the latter half of the 20th century biblical scholars "knew" there had been a Council of Jamnia in the late first century where the Hebrew canon was fixed in response to Christianity. Now this is a theory embraced by virtually no one. But the rise and fall of such theories has little to do with new evidence, and more with arguments over the same old evidence, which gain currency.
Jewish followers. Paul however clearly views Jesus as divine, and Ehrman would surely agree that Paul viewed him as such.
Paul's letters are widely taken to be the earliest Christian sources though, which makes the temporal argument seem a bit off. Luke is coming significantly later, perhaps after John, and in any event Luke taken with Acts shows Jesus as quite divine.
If the Church were really being led by God, why is there so much confusion in the church? I would think that if there were a single authority guiding it, then consensus would increase with time. But like all other religions, factions and confusions increase with time in Christianity, rather than decrease.
Consider than even if the Old Testament account of ancient Israel they are often divided against each other and unclear of what to do. Even as the authors want to present things there is division. Man is forever backsliding and unsatisfied. There is a very comical part of Exodus where, as God is literally splitting the sea for the Hebrews, and they cry out to Moses "why have you led us out here to be caught by the Egyptians. Were their not enough graves left in Egypt that we should die here in the wilderness!"
Factions haven't really increased either. The early church was incredibly diverse, with various sorts of gnostics, Arians, Donatists, docetism. If anything, it was more theologically diverse than today.
This compares poorly to science, for instance. There are arguments in science, but with time, knowledge and consensus increase. This is because science is based on sensory observation and on math, and these are the same for everyone.
Science continually has paradigm shifts where we realize that the way we thought about things before has been entirely wrong. It isn't stable, but goes through massive shifts. Consider the history of understanding what heat was, the dominance of views that proposed an eternal universe prior to the Big Bang Theory, Newtonian absolute space and time versus relativity, the "quantum revolution," the "chaos revolution," etc.
I would say science is much less stable than theology. Protestants, Orthodox, and Catholics can all look back and agree on much in St. Augustine, St. Maximus, etc. What science agrees with attempts at scientific theories from the years 400-800?
If the Holy Spirit were guiding the church, and it were the same for everyone, why would not the churches increase in knowledge and consensus, like in science?
If God acted like you think God should act, sure. But if God is truly God couldn't God just autopilot us into all being saints and agreeing? So even if Christianity led to far more consensus than science you could still throw out the same argument, claiming that "if it isn't perfect, it isn't divine."
I was writing a short story about this. Suppose a second Moon appeared in the sky one day. A giant rosey sphere about four times the size of our Moon in the sky with a huge cross on it, visible by day. How much would it really change?
You might get an initial surge in religion, but I imagine it wouldn't change much in the long term. Denominations would still fight over the meaning of the sign. Muslims could claim it was a trick or the devil or had some other meaning. If the appearance of the thing caused some flooding due to a shift in the tides, this would be taken as evidence of its non-divine nature.
Eventually we'd land probes on the thing and come to understand what it was made of. We'd have theories about ETs and wormholes. People would get used to it and the second moon would become mundane, "that thing that happened."
But if throwing a giant cross in the sky isn't enough, what is?
Interestingly, the Bible starts with God commanding man directly from on high in this sort of obvious way, in a pillar of flame, etc.. Over time, God shifts to speaking to a corporate people through prophets. God now reached man through man. This culminates in God becoming man and speaking to man face to face. Then there is a third switch to indwelling Spirit. God will now live in man, every mind a temple to the Holy Spirit, as St. Paul had it.
Man is expected to mature here. The relationship becomes more hands off. I would consider that if mankind is to become truly self-determining, this can't be otherwise. Divine autopilot or vast signs only work so long as the signs remain. But there is to consider Jesus' claim that it is better if we don't see signs and wonders.
Of course, we tend to look at things in a highly individualistic way these days. How does the individual become free, etc. So the old explanations in terms of mankind as a corporate body maturing and developing seem to lose their hold. We tend to think of our species as in its adulthood, rather than being adolescents, so we expect that the fruits of any historical process should be clear to us by now.