That means that the v.25 is talking about those who are spiritually dead becoming spiritually alive.
Have you never experienced this?
Of course, as you pointed out, v.25 is talking about the so-called "first resurrection" in Revelation 20. But you still haven't understood what spiritual death and spiritual life really are.
I don't read it that way. I don't think the passages warrant adding the word "spiritual" to "death" throughout these passages.
Joh 5:24 Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
These are the ones who already have life. I'll accept your term and call it "spiritual life". They will not come into condemnation, or judgement. Contrast with this:
Joh 5:25 Verily, verily, I say unto you, The hour is coming, and now is, when the dead shall hear the voice of the Son of God: and they that hear shall live.
Do you see the difference? They that hear his voice shall live but what's different about these as compared to those in verse 24?
The answer is that there is no requirement for belief as there is in verse 24 is there? They shall live, but it doesn't say anything about being given spiritual life. They will live physically, as the people Jesus resurrected were raised physically. Now it's true they probably believed and became spiritually alive after their resurrection.
Did Christ literally raise up the dead during his earthly ministry? Yes. Why would he literally raise up the dead? Because he was a nice guy? Because he could? The simple answer is so that people would believe it could be and would be done so in the future resurrections.
As I said this exactly parallels the events in Revelation verse 20.
These two are equivelent:
Rev 20:6 Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
Joh 5:24 Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
And these are equivelent:
Joh 5:28-29 Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice, and shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.
Rev 20:12 And I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works.
They have to be talking about the same thing because it was Jesus Christ describing both things. It was Jesus describing it to John in John, and it was Jesus describing it to John in Revelation. They must be consistent.