What is the communion in grace which the members of the invisible church have with Christ?

The communion in grace which the members of the invisible church have with Christ, is their partaking of the virtue of his mediation, in their justification,[1] adoption,[2] sanctification, and whatever else, in this life, manifests their union with him.[3]

1. Rom. 8:30

   And those whom he predestined he also called, and those whom he called he also justified, and those whom he justified he also glorified.

2. Eph. 1:5

   …he predestined us for adoption as sons through Jesus Christ, according to the purpose of his will … .
   

3. I Cor. 1:30

   And because of him you are in Christ Jesus, who became to us wisdom from God, righteousness and sanctification and redemption … .

Westminster Larger Catechism, Question 69