Revelation 4-5 are often read only for their value in describing worship (worthy is the Lamb….) or their angelology (who are the elders? What are the four living creatures?) While these elements are certainly there, the function of these chapters in Revelation is to introduce the vision of the seven seals. The Lamb is worthy of the same worship applied to God, but this means he is also worthy to open the scroll with seven seals. These seals represent the beginning of God’s judgment on the world.
First, the “door of heaven” is opened, is a common apocalyptic element. The idea of going “up to heaven” may be drawn from Gen 28:17 or Ps 78:23, but is developed in non-biblical apocalyptic into the idea that heaven is closed. Only the visionary is invited to “come up” into heaven.
3 Maccabees 6:18 Then the most glorious, almighty, and true God revealed his holy face and opened the heavenly gates, from which two glorious angels of fearful aspect descended, visible to all but the Jews.
1 Enoch 14:8-9 And behold I saw the clouds: And they were calling me in a vision; and the fogs were calling me; and the course of the stars and the lightnings were rushing me and causing me to desire; and in the vision, the winds were causing me to fly and rushing me high up into heaven.
Second, John hears a “voice like a trumpet.” This too is a common apocalyptic element as trumpets are used to signal an announcement. Perhaps this is a description of some king of ecstatic state. John’s body remains on Patmos, but in his spirit (mind?) he experiences heaven. Paul appears to have experienced the same sort of thin in 2 Cor 12:1-4, in non-biblical apocalyptic 1 Enoch 70-73 and 81 are quite similar.
1 Enoch 71:1-2 (Thus) it happened after this that my spirit passed out of sight and ascended into the heavens. And I saw the sons of the holy angels walking upon the flame of fire; their garments were white—and their overcoats—and the light of their faces was like snow.
Third, as John enters heaven in the Spirit, he sees a fantastic throne (Rev 4:2-3). This vision is very similar to that of Ezekiel 1-3 as well as Isaiah 6, but the main source of imagery appears to be Daniel 7:9-27. Again, there is some element of“stock language” in the description of the throne. Throne imagery is important in Revelation, although John never names the one on the throne. It is as if he cannot find a word to describe the glory of God associated with the throne.
Testament of Levi 5:1 At this moment the angel opened for me the gates of heaven and I saw the Holy Most High sitting on the throne.
John is describing heaven exactly the way any Jewish reader would have expected heaven to look in the late first century. Imagine if he had described heaven like a modern office complex, or Disneyland (the allegedly happiest place on earth) or a resort in the Caribbean. The original readers would not understand the imagery, since they were expecting these sorts of stock images of “what heaven might look like.”
This might be a good warning against using these descriptions to create a list of things about what heaven is really like.