A.T. Robertson Commentary John 5:25

"Verily, verily, I say unto you, The hour cometh, and now is, when the dead shall hear the voice of the Son of God; and they that hear shall live." — John 5:25 (ASV)

And now is (κα νυν εστιν). See 4:23 for this phrase. Not the future resurrection in verse 28, but the spiritual resurrection here and now.

The dead (ο νεκρο). The spiritually dead, dead in trespasses and sins (Ephesians 2:1,5; 5:14).

Shall hear the voice of the Son of God (ακουσουσιν της φωνης του υιου του θεου). Note three genitives (φωνης after ακουσουσιν, υιου with φωνης, θεου with υιου). Note three articles (correlation of the article) and that Jesus here calls himself "the Son of God" as in 10:36; 11:4.

Shall live (ζησουσιν). Future active indicative, shall come to life spiritually.