How much biblical evidence is there, using the Bible alone, that the seven churches in Revelation chapters 2 and 3 represent eras in the Church of God throughout history?
There are four possible ways (that I know of) to understand the messages to the seven churches in Revelation. These are not mutually exclusive, but may all apply.
One, these represent messages to seven literal Church of God congregations in Asia Minor at the time these messages were given to John. That is the most literal and most obvious understanding. I think everyone agrees that this applies. There were seven congregations in Asia Minor, and Christ gives a message to each of them through John.
Second, the traits and characteristics listed in the seven messages can apply to members at any time in the Church of God. With this understanding, when we examine ourselves, we should examine ourselves in light of all the messages, asking ourselves, "Does this apply to me?" Where we find we are at fault, we should repent. So for example, in the message to Ephesus (Revelation 2:1-7), Christ tells them they have left their first love. When I read this, I should ask myself, "Have I left my first love?" If I have, I should take Christ's correction to heart and repent.
Few, if any, I think, have a problem with understanding the messages this way. The evidence that Christ intends all of us to examine ourselves in light of all the messages is in His admonition, "He who has an ear, let him hear what the Spirit says to the churches" (Revelation 2:7, 11, 17, 29, 3:6, 13, 22). Understanding that all seven messages are useful for the whole Church of God for correction and self-examination does not contradict the fact that these were seven messages for seven literal congregations in John's day. Both are true. For, if they only applied in John's day, why would God record them for the Church today?
Even in John's day, in these seven literal congregations, the instruction to hear what the Spirit says to the churches applied to those seven congregations. So each person in those seven congregations should have examined himself in light of all seven messages. Nevertheless, in each congregation, one condition predominates or is the condition of the majority.
A third possible way to understand and apply these messages is that they represent eras in the true Church through history. This is implied by the fact that the seven churches in Asia Minor were on a mail route, and that there was a sequence of mail delivery from first to last among those seven cities that matches the order in which Christ gives His messages. The implication is that this is not accidental or coincidental, but has a purpose, and that purpose is to show the predominant spiritual condition of the Church of God in seven stages or eras in Church history. In this way, Christ can talk to the Church of God at various times in history, giving the Church the message it needs during each era or stage, from the Bible. There were many more congregations in the whole Church of God in John's day than just these seven, but God chose these seven, all on a mail route, to give messages to in Revelation, and the messages are in the same order as the cities on the mail route, implying a time order or sequence.
This idea does not contradict the first two, but supplements them. While in each era, there can be individuals being in any of the seven conditions described, the predominant or majority condition will be that as described in the message for that era. So in the Sardis era, most members or the largest number of members would be in the Sardis condition, and the Sardis condition would be the predominant spiritual condition or state. Nevertheless, there can be individuals in other conditions, such as the Laodicean condition or the Philadelphian condition, during the Sardis era - that is why Christ says, he who has an ear, let him hear what the Spirit says to the churches, all of them. But while members should examine themselves in light of all seven messages, they should pay special attention to the message for the era they are in.
Not everyone agrees that these messages are for Church eras. Mr. Armstrong believed it, and many in the Church of God today believe it, but some do not. Also, some in traditional, mainstream religion believe that idea and some do not.
The fourth possible application is that these messages will be for several or all seven churches that will exist as organizations or fellowships or congregations at the end, just before Christ returns. I suppose the main supporting evidence for this is that the whole book of Revelation is intended to apply to end-time events, and there may be an implication in that - that the application of the seven messages will be for seven literal churches at the end time. This again is not exclusive of the first three applications. All four might possibly apply. Some in the Church of God may believe that four or all seven churches might exist as individual organizations just before the return of Christ.
But how much evidence is there that these messages represent and apply to eras in the Church?
If you are talking about evidence in the Bible only, there is not much - just what I mentioned, the implication that these represent a sequence of conditions because the messages are given in the same order as the cities were visited in a mail route. That seems reasonable, but may not be firm proof.
But when you combine what the Bible says with history, there is more evidence.
I do not believe the doctrine of the eras of the Church just based on the Bible alone. Nor do I believe that doctrine based on Mr. Armstrong's teachings. I believe it because of the combination of what the Bible says plus history, especially the history of the Church of God in the last 100 years.
I see the fulfillment of these messages, the last three (Sardis, Philadelphia, and Laodicea), in the recent history of the Church of God. That is what convinces me. Not just that the messages are given in the same sequence as a mail route. That, by itself, does not prove the issue for me. But when I see the last three eras unfolding, living through two of them, that is what proves the case for me beyond doubt.
The Church of God Seventh Day seemed to be dead in a sense because they were not willing to learn new knowledge from the Bible and they were not doing a powerful work. During Mr. Armstrong's day, the Church grew rapidly because we had an open door for preaching the gospel, as promised to Philadelphia (Revelation 3:8, 1 Corinthians 16:8-9, 2 Corinthians 2:12, Colossians 4:2-4). Today, the Church of God is in a scattered, weakened condition, as you would expect in the Laodicean era.
Is belief in the eras of the Church a critical doctrine for salvation? No. You and I will be judged on the basis of our faith in God and Christ, our repentance, and our obedience to the spiritual law of God. We must overcome our sins. We must trust and believe in God and Christ. In that sense, the doctrine of the eras of the Church is not critical for salvation. But if that doctrine is true, and I believe it is, it can be helpful for our spiritual growth and for doing God's work, as is all the knowledge God gives us.
Can the idea of Church eras be misused? Can it become an excuse and a tool for division, competition, and strife in the Church of God?
Certainly. Each of several groups claims to be Philadelphian and accuses other groups of being Laodicean. But it is not just the eras of the Church that can be misused that way. It is the messages themselves that are being misused, used for strife and division. You don't have to believe in eras to claim to be Philadelphian and accuse others of being Laodicean. In fact, the idea that one organization is Philadelphian while others at the same time are Laodicean has nothing to do with eras. An "era" is a period of time. It is not an organization.
So if we are in the Laodicean era, then it is the Laodicean era for everyone in the Church of God. You might be Philadelphian, and I might be Sardis, but the majority is Loadicean. It is the same era, the same time period in the history of the Church, for all organizations. Right now, as I write this, the year is 2014. It is 2014 for everybody. It is not 1924 for you and 1954 for someone else and 2014 for me, all at the same time. An era is a period of time that crosses organizational boundaries.
If an organization wants to use the seven messages in Revelation to boast against other organizations, it does not need eras. It can simply say, we are Philadelphian and you are Laodicean. That kind of tooting of one's own horn at the expense of others does not require eras. It would probably happen anyway if no one ever heard of "eras". In fact, if there were no eras, it would be just as easy, maybe easier, for any organization to boast, "The message for Philadelphia applies to us and the message for Laodicea applies to you."
In the matter of proof or evidence of eras, is it proper to use history or current events to help understand the Bible? Yes it is. We certainly do that with other doctrines. We do that with the history of Israel to understand who Israel is today. It is the combination of the Bible with history that helps us understand.
Take for example the doctrine that God is working out a 7,000 year plan for the salvation of mankind, with the first 6,000 years showing the fruits of man's self rule under Satan's influence and the last 1,000 years showing the fruits of Christ's rule. How much proof is there in the Bible alone for that doctrine?
There is some evidence, but not a lot. Maybe not enough for absolute proof. We have the statement that one day is as a thousand years and a thousand years as one day (2 Peter 3:8). We have the seven day week and the weekly Sabbath (Exodus 20:9-11). Perhaps we have the example of Adam not living a full thousand years after God told him, in the day you eat of the tree of the knowledge of good and evil, you will die (Genesis 2:15-17, Genesis 5:5). And we have the statement that Christ will rule the earth with the saints after His return for a thousand years (Revelation 20:4-6).
If that is all I had to go by, I am not sure I would be absolutely convinced that God is definitely working out a 7,000 year plan. There is no direct statement that it would be 6,000 years from Adam's creation and sin to the return of Christ. The statement that a thousand years is as a day might mean no more than God's perspective on time. I might think that the scriptures I mentioned are good circumstantial evidence of a possible 7,000 year plan, but not absolute proof.
But what convinces me is the combination of that with something else in the Bible and with history. God told Daniel that at the time of the end many would run to and fro and knowledge would increase (Daniel 12:4). That has been fulfilled right near the end of about 6,000 years of human history from Adam till now, according to Bible chronology. I do not believe that is a coincidence. The explosion today of knowledge and transportation at the end of 6,000 years, combined with the weekly Sabbath and the statement about a day being as a thousand years and the coming 1,000 year reign of Christ, is what convinces me of the 7,000 year plan of God. And it is the same kind of combination of scripture and history that convinces me that the seven churches of Revelation represent eras in the Church of God.