And he saith unto me,
Seal not the sayings of the prophecy of this book:
for the time is at hand.
Revelation 22:10
"So here are three treatises, all ending only with the end of the
world,—
The seven churches, you will see if you look carefully, are seven 
definite epistles to the true church in its seven periods.
The seven trumpets are seven phases of the history among the nations
of the world, as they are connection with the church history. Each of
the trumpets is directly connected with the church history; particularly
the first four come as a consequence of the apostasy that is shown in
the seals.
The seven seals are composed of seven steps marking the apostasy, the
Reformation, and the events connected with the coming of the Lord.
The seven churches are seven instructions to Christ’s church itself.
The seven seals take the church of God at the beginning, 
---and show a
step away, and another step away toward the world, and another step away
toward the world, until the apostasy is complete;
---then the result of
the apostasy is marked in the slaughter of the saints of God; and after
that the vindication of the saints, the signs of the Lord’s coming, and
the sealing and deliverance of the remnant.
When you have searched out and carefully read the full history of the book of Daniel, especially the ten kingdoms, it is easy to read, in the eighth chapter of Revelation, the whole history of the first four trumpets, because the history is there.
The first four trumpets occur in the same period as does the rise of
the ten kingdoms. And the rise of the ten kingdoms was upon the fall of
Rome.
Q: But what caused Rome to fall?
A: The union of church and state; the
covering of all the iniquity of paganism, with only the forms and the
profession of Christianity. The forms of Christianity, filled with the
life and spirit of Satan,—it was that which caused the ruin of the Roman
Empire." A.T. Jones