The final question is on how union with Christ should affect the church’s piety:
It should dramatically and deeply impact it. I can draw attention to three ways.
First, in the Lords’ Supper we do not have communion with the benefits of Christ—as if we were united to the doctrine of justification—but with Christ himself. Christ’s benefits flow from that.
Second, in relation to assurance, we are not acceptable to God on the basis of our state of mind or heart at any given moment, not that that is unimportant. Since we are united to Christ, the Father regards us exactly as he does his Son and has done from eternity! That is why we can call on him as “Our Father . . .”
Third, in relation to death. In union with us, God the Son has experienced human death and burial according to his flesh. Following this, in union with him, we will share his resurrection. Before I forget to say so, Christ’s resurrection and ours are the same reality, separated by indefinite time; the resurrection has already begun with his in AD 30, ours following. If you read 1 Corinthians 15:12-49 carefully you will see this.