A phrase found in Revelation
The wording appears four times in Revelation. John sends grace and peace from God, from the seven spirits before God's throne, and from Jesus Christ (Revelation 1:4-5). Later, Jesus is described as holding the seven spirits of God, while seven burning lamps before the throne are identified as those spirits (Revelation 3:1; Revelation 4:5).
At first, that can sound as though God has seven separate Holy Spirits. But Revelation is packed with visions and symbols. It speaks of seven churches, seven lampstands, seven seals and seven trumpets. In this book, seven commonly communicates fullness or completeness rather than simply a literal count.
And out of the throne proceeded lightnings and thunderings and voices: and there were seven lamps of fire burning before the throne, which are the seven Spirits of God.
The Holy Spirit in his fullness
For that reason, many Christians understand the seven spirits as the one Holy Spirit shown in the completeness of his work. The setting supports this. The spirits are before God's throne, included in a greeting of grace and peace, and closely connected with the Father and Jesus Christ (Revelation 1:4-5).
Revelation also pictures the Lamb, Jesus, with seven eyes. John explains that these are the seven spirits of God sent out into all the earth (Revelation 5:6). The image shows God's perfect sight and the Spirit's worldwide activity. Nothing is hidden from Christ, and his Spirit is not limited to one place.
And I beheld, and, lo, in the midst of the throne and of the four beasts, and in the midst of the elders, stood a Lamb as it had been slain, having seven horns and seven eyes, which are the seven Spirits of God sent forth into all the earth.
What about Isaiah's description?
Some readers connect this phrase with Isaiah's prophecy about the coming Messiah. Isaiah says the Spirit of the LORD would rest on him, and then describes wisdom, understanding, counsel, might, knowledge and the fear of the LORD (Isaiah 11:2). These are not presented as separate spirits. They describe the rich and perfect character of God's Spirit at work in the Messiah.
That connection can help explain the idea of fullness, even though Isaiah does not use the exact phrase "seven spirits of God". The KJV wording gives one Spirit of the LORD and six closely related qualities. Revelation's number seven may draw on the same biblical way of portraying God's complete, life-giving presence.
Not a puzzle to fear
A smaller number of interpreters have wondered whether the phrase refers to exalted angels, since Revelation does mention seven angels who stand before God (Revelation 8:2). Still, the links with Jesus, the throne, the lamps and the Lamb's eyes lead many Christians to see the Holy Spirit as the better reading.
You don't need to solve every detail before receiving the comfort of the vision. God is not distant or short of power. Through his Spirit, he sees, strengthens, guides and carries out his purposes in all the earth. Read Revelation slowly, and let its pictures point you towards worship of the Father and the Lamb.