Revelation 4:1

I will show you
This is the primary purpose of the Revelation being given John (Rev. Rev. 1:1+, Rev. 1:19+; Rev. 22:6+). The scenes in the book of Revelation often follow a pattern where a heavenly setting is described followed by an earthly setting:

Each Vision “in heaven” is preparatory to the Vision afterwards seen “on earth”; and what is seen “on earth” is the carrying out of the Vision previously seen “in heaven.” The one is mutually explanatory of the other. The heavenly Vision explains what is going to take place upon the earth; and the utterances in each heavenly Vision set forth the special object of the earthly events which are to follow. The former Vision of each pair, is therefore, the key to the latter.⁷

things which must take place after this
The things to come are sure for they must take place. God’s prophetic word cannot be broken (John John 10:35). This is why the sword extends from the mouth of Jesus—the will of God, once having been spoken forth, is unstoppable (Rev. Rev. 1:16+; Rev. 19:15+). After this is perhaps better translated after these [things]. It is the same phrase which begins the verse: μετὰ ταῦτα [meta tauta] . This verse follows “the things which are” and Jesus is now introducing the next major topic—the things which are yet future to John’s time.

Notes

¹ New Electronic Translation : NET Bible, electronic edition (Dallas, TX: Biblical Studies Press, 1998), Rev. 4:1.

² Many red-letter Bibles seem unwilling to identify the voice as being that of Jesus for they render the words of this voice in black but the words of the voice speaking in Revelation Rev. 1:10-11+ in red. An exception is the KJ2000 Bible, http://life-equals-jesus.org/Couric/KJ2Khome.html, available from http://www.spiritandtruth.org/download/tools/index.htm.

³ Donald Grey Barnhouse, Revelation (Grand Rapids, MI: Zondervan Publishing House, 1971), 88.

⁴ Merrill C. Tenney, Interpreting Revelation (Peabody, MA: Hendrickson Publishers, 1957), 141.

⁵ Jerome Smith, The New Treasury of Scripture Knowledge (Nashville, TN: Thomas Nelson Publishers, 1992), Rev. 4:1.

⁶ Arnold G. Fruchtenbaum, The Footsteps of Messiah, rev ed. (Tustin, CA: Ariel Ministries, 2003), 165.

⁷ E. W. Bullinger, Commentary On Revelation (Grand Rapids, MI: Kregel Publications, 1984, 1935), 211.