I'm not referencing what you said. Non-historically, our union with Christ goes back to the eternal beginnings of the covenant of grace in election. "According as he hath chosen us in him {Jesus Christ} before the foundation of the world, that we should be holy and without blame before him" (Eph. 1:4).Originally posted by piningforChrist
No.
Justification is not what unites us to Christ. We are united to Christ, historically, at the moment of our regeneration, "in our effectual calling," as our confession (if not yours) affirms. Faith is the instrumental cause. Justification (as well as adoption and sanctification) is a benefit partaken of by those who are effectually called.
I did not say historically.