John 15:3 You are already clean because of the word which I have spoken to you.
This cleansing is effected through hearing, believing, and obeying the Word. The word of Christ is spoken to all believers; and in it is a cleansing virtue as it works in grace, and works out corruption. We have been purged from the guilt and power of sin, moved from the wild vine and grafted into the New True Vine.
Those who have repented and trusted in Christ alone are already clean (made holy). Rom 11:16 “For if the firstfruit is holy, the lump is also holy; and if the root is holy, so are the branches”. Believers are born of the water and the Spirit (John 3:5). The water here is not baptism but cleansing (regeneration), Titus 3:5 “not by works of righteousness which we have done, but according to His mercy He saved us, through the washing of regeneration and renewing of the Holy Spirit”. Cleansed first before the indwelling, (Rom 6:6, Lev 15:13, Eze 36:25).