Ephesians 1:4, “For he chose us in him before the creation of the world to be holy and blameless in his sight.”
This is the only place in Paul’s writing where this phrase occurs. It does occur a number of times in the NT.
It denotes the divine act of election as taking place in eternity.
Time belongs to the created order: believer’s present experience of the blessings bestowed by God is the fulfillment on the temporal plane of his purpose of grace toward them conceived in eternity.
As the fulfillment is experienced “in Christ”, so it is in him that the purpose is conceived.
Jesus is God’s chosen one par excellence, so it is by union with him, according to the divine purpose realized in time, that others are chosen.
Jesus is the foundation, the origin, and the executor of election: all that is involved in election and its fruits depends on him.
Calvin says that “in Christ” confirms the freedom of election: “For if we are chosen in Christ, it is outside ourselves. It is not from the sight of our deserving, but because out heavenly Father has engrafted us, through the blessing of adoption, into the Body of Christ. In short, the name of Christ excludes all merit, and everything which men have of themselves; for when he says that we are chosen in Christ, it follows that in ourselves we are unworthy.”