23 But the hour cometh, and now is, when the true worshippers shall worship the Father in spirit and in truth: for the Father seeketh such to worship him.
24 God is a Spirit: and they that worship him must worship him in spirit and in truth.
When he speaks of “worship in Spirit and truth,” Jesus may have in view the common identification of the Spirit with prophecy in ancient Judaism, as well as Old Testament passages about charismatic, prophetic worship (especially 1 Sam 10:5; 1 Chron 25:1–6). Given the general belief that the prophetic Spirit was no longer active, Jesus’ words would strike ancient ears forcefully. The future hour (4:21) is present as well as future; Jesus makes the character of the future world available to his disciples in their present lives (see comment on 3:16). For oppressed Jews and Samaritans longing for the future promise, this was also a striking statement.
Craig S. Keener, The IVP Bible Background Commentary: New Testament (Downers Grove, IL: InterVarsity Press, 1993), Jn 4:23–24.