Introduction to Revelation

The Book of the Revelation of St. John consists of two principal divisions. 1. Relates to "the things which are," that is, the then present state of the church, and contains the epistle of John to the seven churches, and his account of the appearance of the Lord Jesus, and his direction to the apostle to write what he beheld, ch. 1:9-20. Also the addresses or epistles to seven churches of Asia. These, doubtless, had reference to the state of the respective churches, as they then existed, but contain excellent precepts and exhortations, commendations and reproofs, promises and threatenings, suitable to instruct the Christian church at all times. 2. Contains a prophecy of "the things which shall be hereafter," and describes the future state of the church, from the time when the apostle beheld the visions here recorded. It is intended for our spiritual improvement; to warn the careless sinner, point out the way of salvation to the awakened inquirer, build up the weak believer, comfort the afflicted and tempted Christian, and, we may especially add, to strengthen the martyr of Christ, under the cruel persecutions and sufferings inflicted by Satan and his followers.

-- taken from Matthew Henry's Concise Commentary