John 17:21 — the oneness Jesus prays for is relational unity via the indwelling Spirit and Christ's mediation, not ontological Trinity participation

Mike identifies two key themes: (1) The indwelling of the Holy Spirit — believers are filled with the Spirit (major theme in John 14-16), which is the new covenant mechanism for the Trinitarian relationship in believers. (2) The humanity of Christ — Jesus as the perfect man in right relationship with the Father is the model/template. He has lived unstained and can give believers his righteousness so they can share in that relational quality. This is not about ontological sameness with the Trinity but relational Oneness through Christ as mediator and the Spirit as indweller.