I appreciate the following selection from Michael Horton’s Justification (Vol 2). It’s about union with Christ, justification, sanctification, and glorification:
Union is not a goal but the source of our life. Chosen in him [Christ], redeemed by him, and crucified, buried, and raised with him, we share in Christ’s pioneering journey in an ‘already’ and ‘not-yet’ manner. Justification is the fundamental turning point in the sinner’s status before God, while sanctification is the turning point in the sinner’s condition, and glorification will be the turning point in the whole existence of the saints.
Although we will be all that he is in his glorified humanity, we are not yet raised bodily. Yet we have been raised from spiritual death, justified and definitively renewed. We are being conformed to the image of Christ daily, suffering in the joy of the prize that has already been won for us. ‘There is therefore now no condemnation for those who are in Christ Jesus. (Rom 8:1). Although we still struggle mightily against Satan, sin, and the realities of a fallen world, Christ has already subdued Satan. “The God of peace will soon crush Satan under your feet’ (Rom 16:20).
Union with Christ (or the ‘great exchange’) is the braoder intersection where rival perspectives demand a fork in the road – the false choices that we have met frequently along the way – but where, in a more integrated account, they meet without any contradiction. Covenantal and apocalyptic, personal and corporate, soteriology and ecclesiology, the historia salutis and the ordo salutis, forensic justification and transforming renewal, faith and works all find unity without conflating one with the other.