Marshall on living in Union with Christ:
“…you might think that you are unworthy to have such a great gift as union with Christ. Remember, however, Christ shed his precious blood to redeem you. That precious blood will enable you to miraculously advance in holiness through your union with Christ. Union with Christ is not a privilege you earn by your sincere obedience, or by your own attempts at holiness. Your union with Christ is not a reward of your own good works. Rather, union with Christ is a privilege that God gives to every Christian when they first become a Christian! Right when you enter into the Kingdom of God, you also enter into union with Christ!
This union with Christ is the foundation for all of your obedience to God.
All of your good works as a Christian flow out of your union with Christ. All of your sincere obedience to the law is the fruit of your union with Christ.”
Walter Marshall, The Gospel Mystery of Sanctification