Why do people believe that the 7 kingdom parables and the 7 churches of revelation represent the same things?

There is a great danger of confusing two distinct things here, but that can be avoided once it is made clear how different the ‘Historicist’ view is to the comparatively recent ‘Dispensationalist’ view regarding the Revelation. There is not the mingling of those two schools of thought as some imply. I intend to make that clear at the outset before progressing to the question of the 7 kingdom parables in Matthew’s gospel being taken by Dispensationalists as parallel to the 7 congregations in Revelation. First, a brief history of developments with interpreting the Book of Revelation is essential. I quote:

The Contemporary [Praeterist] Interpretation: This puts the entire book into past history. It views the Revelation as having been fulfilled in the early ages of the church. This interpretation places every event throughout the narrative as contemporary with the first century. But a device underlies this interpretation. At the time of the Reformation the reformers identified the papacy and its political influence with the Beasts in Revelation. This was of great influence. However, the Contemporary Interpretation robbed the reformers of such an application. According to the Contemporary, or Praeterist interpretation, the whole book had long been fulfilled.

The Historicist Interpretation: This views the Book of the Revelation – with the exception of the prologue and the epilogue – as a continuous unfolding of the history of the church in the world. Therefore the narrative answers in sequence to the history of the church, or of the world, or both. This interpretation commences with the apostolic age and continues to unfold to the end of time. There was no difficulty therefore in this interpretation of identifying the ‘Beast’ with the papacy, or with its influences over the worldly powers. This was the view of the reformers. At first Rome and its satellite European Community countered this view with the Contemporary Interpretation. Then a more subtle concept began to be put forth by the papacy.

The Futurist Interpretation: There can be little or no question that this view was developed as Roman Catholic counter-reformation propaganda, the Contemporary, or Praeterist, Interpretation having failed in its attempt to refute the reformers’ Historicist explanation… The Futurist Interpretation, however, put everything in the future, robbing the reformers of their ammunition at a stroke.

The Futurist Interpretation views the church prophetically from the day of Pentecost till the second coming of Christ in historical sequence throughout Chapters 2 and 3 of the book. In Chapter 4:1 a secret rapture of the church is proposed… It follows therefor that the prophetic narrative of events from Chapter 4 to Chapter 20 have nothing to do with the church. It is presumed that this is to do with Israel over a future seven year period of tribulation. In Chapter 20 the thousand years are taken literally, assuming Israel on earth, and the church suspended above it in heaven for the entirety of this period…

This astounding scheme was recovered from oblivion – the Reformation by then seeming to be of little consequence – largely by the ecumenical meetings for prophecy at the castle of Lady Powerscourt in Ireland. J.N. Darby and other early brethren leaders, many of them clergymen, featured prominently. The Plymouth Brethren adopted and propagated this originally papist subterfuge with great vigour from the 1830’s onward. After the division at Plymouth, the American Schofield had the temerity to incorporate this papist propaganda, with other horrific schemes, such as dispensationalism, interleaving such things so as to add them to the Holy Bible, newly dubbed ‘The Schofield Bible’.” The Revelation of Jesus Christ by John Metcalfe, pp 13-15 (published 1998)

He then details The Resumptive [or Spiritual] Interpretation, which he holds to, where the entire age of the church is revealed seven times over, culminating in the last judgment, each presentation adding more details and principles to the monumental struggle between the church on earth and the demonic, invisible powers trying to crush her, to this day. Regarding your question, he points out that Rev. 2:10 (the church in Smyrna) had, in those days, the faithful martyr Antipas, and such persecution would continue till Christ returned (p 47). Thus, the message to the 7 churches speaks to the persecuted saints in every age from Christ giving the Revelation, to his sudden appearing. He adds:

“To suggest that each of the seven churches represents an historical period following on from that which preceded it, and leading up to the next named church which is prophetic of a succeeding era – each following one after the other so as to constitute the entire history of the church in sequence – is nothing short of imbecilic.” (Ibid. p 59)

Thus it is clear that Christians holding to this Resumptive [Spiritual] Interpretation abhor that of the Futurists. Nor did the Reformation Historicist view uphold the 1800’s ideas of the Futurists. Both those groups maintained that “The Last Days” had begun in the 1st century A.D. and continue to this very day – Hebrews 1:1-2.

Certainly, the Futurists (Dispensationalists) draw parallels between the 7 kingdom parables of Matthew 13 and the 7 churches detailed near the start of the Book of Revelation, as has been graphically shown in a previous answer here. But whatever the Historicists and the Resumptives have said about the 7 kingdom parables in Matthew 13 is not linked by them to Revelation’s 7 churches, as if they need to be interpreted together. Yes, the 7 parables teach spiritual principles, many of which can also be spotted in the Book of Revelation, throughout its entirety. But that is quite different to the Futurist (Dispensationalist) chart of parallels.

An excellent summary of this is given in this book which provides 4 parallel commentaries:

“Since they are not primarily predictive in character, the interpretation of the seven letters is not a matter of great controversy among the four approaches surveyed in this commentary. With one point of exception: Interpreters of the preterist, and the spiritual schools, and many futurists as well, understand the letters to be addressed to the actual, historic churches named in them, and by extension to any churches that may find themselves in similar circumstances to theirs. Beyond this, they seek no additional, hidden meaning behind them. However, those of the historicist school, and some of the futurist school, have called attention to certain parallels between the individual letters and successive periods of church history, from John’s day until the end. They conclude that the seven letters present a panorama of the age of the church. Revelation – Four Views, pp 62-63 Ed. Steve Gregg

He adds that this is “found chiefly among futurist commentators – particularly among many (but not all) dispensationalists.” He then takes 17 pages to detail each of the 7 churches letters, with comments on all four schools of interpretation, so if you really want to thrash this out, you would do well to get the book I quoted from, above. I glanced through all 17 pages but although various scriptures were appealed to, including from Matthew’s gospel, nothing from chapter 13 was mentioned.