John’s grand prophetic experience began on “the Lord’s day” (Revelation 1:10) indicating that separation of a day to the Lord, as in the Sabbath of the Old Testament, was still in practice at least by John (though historically it would seem that all Jews of the time who received Jesus as their Messiah would continue many of the practices that had become the cultural norm—particularly the celebration of Sabbath). Such a practice, it can be determined, yields empowerment by the Holy Spirit in the exercise of supernatural gifts. This is very logical in the sense that setting aside a period of time to surrender the normal cares of life to dedicate one’s self wholly to seeking God (whether through Sabbath, fasting, or many other ways in which this goal can be accomplished), that a person will be spiritually refreshed, opening himself or herself to deeper intimacy with God. That intimacy, then, yields the outflowing of the gifts of the Holy Spirit. The book of Revelation is demonstration of this truth, since the entire message stems from John’s Sabbath experience.
The prophecy began with John hearing “a loud voice like a trumpet.” The word translated “trumpet” is shophar in the Greek, which is a slightly different instrument from the modern trumpet; its principal purpose is making announcement or warning. In this case, Jesus is announcing to John the beginning of a prophetic word so enormous in magnitude that the hearer requires a strong preparation or warning. Therefore, both purposes of the shofar are in use here as it is the simile relating to Jesus’ voice. The announcement from this voice like a shofar instructs John to communicate with the seven churches everything that he is about to share with him, as it is not a message merely for John, but for all of God’s people as represented by these seven churches–the purpose in all types of empowerment provided through the Holy Spirit.