Like I said, I am not well-versed in Darby's writings or teachings. And, of course, I really don't care what Darby taught. His views had no influence on my views on eschatology. I know many people who embrace the idea of a rapture who just don't know who Darby is.
I do have a couple of comments though on what you've just posted. Please don't mistake this for any sort of smug attempt to "call you out" or as any sort of public rebuff/rebuke. I simply want to share a few things that came to mind when reading your post.
You said, "There's no doubt he was the earliest and leading propagator of these ideas..."
Actually, I believe that there is doubt. That is part of the reasons why there is a never-ending debate on this issue. Sometimes, the words "no doubt" often are used as a precursor to a discussion to end it before it begins (or to offer a conclusion). It can become a "shutdown" statement used to digress and pull the discussion in a certain direction rather than by conversational analysis.
In this case, you're saying that there is no doubt that one man -- Darby -- originated this concept (of a "rapture" or gathering of the Bride before the Lord's wrath is poured out upon the world).
Normally, I would ask what led you to this conclusion. What research did you perform? Is this a conclusion drawn from others who have staked this claim? Are you actually well-read into what Darby, the writings of his contemporaries or whatwas written or taught alongside other believers over the last 2000 years (for comparison's sake)?
This oft-repeated belief -- pointing the finger at John Darby -- has been repeated many times by teachers, books and websites that espouse the view that the Bride of Christ will not be gathered prior to the wrath of God being poured out upon the Earth. In the times that I have inspected the claims (including books), they seem to be somewhat short on proof. Yes, they can point to things that Darby has written. Yes, they can point to some things that are attributed to Darby.
However, the statement itself is very wide. The evidence is often presented as not being available because the idea is that it doesn't exist (i.e., the idea of a gathering of the Bride prior to the wrath of God on the Earth). Thus, if those individuals cannot find it, then they deduce that Darby must be the guy who came up with it!
I sometimes wonder if it is the same sort of circular citations that are similar to the KJV-Only phenomenon. The books and websites often quote one another rather than by presenting evidence that no one else prior to Darby had any such view.
You also wrote, "...if one knows nothing of Darby and his "movement" then one knows little or nothing about the origins of the pre-trib belief."
I disagree. First of all, this statement relies upon the notion that the previous statement is absolutely true and beyond reproof.
And, yes, there is at least some anecdotal written evidence from early church writing that indicated that some early Christians at least believed in protection during the time of God's wrath (or even removal prior to it). While such examples are few in number, one could also point out that there aren't exactly large libraries of early church writings to be seen (and most never touched on eschatological specificity).
Since there is very little Christian writings that exist from the first century (partially because literacy wasn't common, printing didn't exist and writing materials were hard to come by and those that did exist decomposed by time), this primary belief cannot be proven.
I would touch a little further on your statement. Does one have to know about Darby to believe that the idea of a "rapture" is possible? I would say no.
There are many believers who embrace the idea of a "catching away" prior to the wrath of God. Like I said, many of them really don't know who Darby is. I would think (or hope) that many of them may have studied this and attributed their belief to a Biblical foundation.
This does raise a very big issue in the Church today.
Many people believe in particular doctrines because they are taught to believe in those doctrines. There are probably people who believe that the rapture is indisputable because they were taught this by their local church and favorite Bible teachers. The weight of their own research is in reliance -- relying upon the research and "expertise" of others.
This is a flawed perspective no matter what we believe. Men -- and Bible teachers -- are fallible. We cannot blindly "follow" what they've said without questioning, testing or proving it from Scripture. Every preacher of the Gospel included on SermonIndex is fallible. We are all confined to this side of that "glass darkly."
Even if we go back to the Early Church, we find some corruption and compromise of the faith early on. Many of these are mentioned in the Book of Acts and in the epistles.
Furthermore, by the time of Constantine (b.272 A.D.), the heresies of pagan Rome were already being grafted into an eventual Empire-regulated "official" church. There was corruption found in "Christian" writings before and after the Edict of Tolerance and Edict of Milan. Many would even argue that the official state "church" had become little more than a compromised tool of the Roman Empire.
Most importantly, the discussion of doctrines should be done primarily by Biblical exegetical study (and discussion) rather than by pointing at quite limited anecdotal manuscript evidence (scarce as it is) from the centuries AFTER the Gospels and epistles were written.
Even as limited as it is, I think that we would be hard-pressed to find someone who has sifted through every ancient manuscript attributed (at least in part) to Christianity. Moreover, the time from the beginning of the Church until Darby is roughly 18 centuries. That is a lot of time (and evidence) required to sort through before we can declare such a "no doubt" statement.
Again, I hope that you didn't take this wrong. I am not motivated to point out any perceived flaw in your post. Rather, I think that it is important to approach this issue (and all non-essential doctrinal discussions) with the understanding that most of us are not here to take sides on an issue but to search for truth.
Sometimes, even after much study, we still don't arrive to a point where we can honestly say "yea" or "nay" on such matters. This is despite amazing access to materials that believers in the past never had access to.
This is why I think that it is always good to revert to the simplicity of the faith. As nice as it is to have so many resources (e.g., concordances, Bible dictionaries, commentaries, books, etc.), it is interesting to think that none of such things were available to the early believers. Many of them didn't even have copies of the Bible (and the New Testament was a set of books and letters passed between the local churches).
When people ask me about my views on eschatology and, specifically, the idea of a "rapture," I tell them that I am not certain. However, I tell them that I am certain about something much more important -- the need to be prepared. This preparation only comes about by keeping our eyes on the Lord. We must seek God always -- in prayer, study of the Word and worship. I believe that this will keep us during any period or trial, tribulation and, yes, wrath that we may or may not have to endure.