Thank you for contacting BibleAsk.
“And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held: And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?” (Revelation 6:9,10).
John was viewing pictorial representations, and that the rules governing the interpretation of such prophecies must be kept in mind when the meaning of the various symbols is sought (Eze. 1:10). John saw an altar at the base of which lay the souls of martyrs. As with the details of a parable, not all features of a prophetic symbolization necessarily have interpretative value. This cry was figurative, as was the cry of Abel’s blood (Genesis 4:10).
It appears that the symbolization of the fifth seal was presented to encourage those who faced martyrdom and death, with the assurance that despite the seeming triumph of the enemy, vindication would ultimately come. Such an encouragement would be particularly heartening for those living in the time of the terrible persecutions of the later Middle Ages, but more especially during the time of the Reformation and after. To them, it must have seemed that the long period of oppression would never end. The message of the fifth seal was a reassurance that the cause of God would ultimately triumph. The same encouragement will come to those passing through the last great conflict.
Any attempt to interpret these souls as the disembodied spirits of departed martyrs doesn’t agree with the rules of interpretation of symbolic prophecies. John was not given a view of heaven as it actually appears. There are no white, red, black, or pale horses there with warlike riders. Jesus does not appear there in the form of a lamb with a bleeding knife wound. The four beasts do not represent actual winged creatures of the animal characteristics noted. Likewise, there are no souls lying at the base of an altar in heaven.
For a study on souls and the state of the dead, please check the following link: https://bibleask.org/bible-answers/112-the-intermediate-state/
In His service,
The BibleAsk Team