Jesus asks the Father to sanctify the disciples in the truth and declares, 'thy word is truth.' He then says that for their sake he sanctifies himself so that they also may be sanctified in truth.
Jesus in Context
Sanctify Them in the Truth
To 'sanctify' is to make holy or consecrate for God's purpose; Jesus prays for his disciples' consecration in truth and then says that he consecrates himself for their sake.
Introduction
Historical and Cultural Context
The Greek hagiazo can mean to make holy, set apart, or consecrate for sacred service. Because Jesus is not confessing moral impurity, his statement that he 'sanctifies' himself is best understood as self-consecration to the mission and sacrificial work before him. Biblical priests, offerings, places, and people could all be set apart to God. The disciples' sanctification is likewise connected to their being sent into the world rather than withdrawn from it.
Why It Matters
The cultic background clarifies that holiness here is both moral and vocational. The disciples are set apart for God's truth and mission.
Jesus' own consecration supplies the pattern and basis: he devotes himself wholly to the Father's saving purpose as he approaches the cross.