The expression, “the seven spirits,” occurs 4 times in Revelation. I have explored and pondered what it means and found the key to understanding is in the spiritual meanings of the number seven. Seven occurs 463 times in the Bible and 83 times in the New Testament, including 31 the Revelation of John.
The explanation most easily understood and that I find most spiritually discerned comes from a profound book, Kingdom Come. It was written by Sam Storms on the book of Revelation. Sam also presents a series of sermons on the book of Revelation. Here’s what he writes:
I believe there is a better solution, one that is more consistent with John’s use of numerical symbolism. On this view “seven” is not numerically precise but points figuratively to the idea, as it often does, of fullness or completeness (see Rev. 1:4, 20; 4:5; 5;6). As in in Revelation12:3 and 13:1-2, notes Beale, “fullness of oppressive power is the emphasis here.
The Lange commentary gives us two other things to consider.
The seven spirits are not seven properties of the Holy Spirit. We must likewise distinguish from these seven spirits the Spirit who speaks to the churches.
John writes of the seven spirits in Revelation 1:4-6; Revelation 3:1; Revelation 4:1-8 and Revelation 5:1-10
John writes of the Holy Spirit speaking to the seven churches in Revelation 2:7; Revelation 2:11; Revelation 2:17; Revelation 2:29; Revelation 3:6; Revelation 3:13 and Revelation 3:22.