Answer
All three persons of the Trinity, the Father and the Son and the Holy Spirit, were and are involved in our salvation. The Father planned our salvation from eternity past, chose his people in spite of who we would be, chose us in grace, chose us in Christ, and covenanted with the Son that the Son would come to redeem us. He gave us to the Son, as Jesus says in his prayer in John 17, that Father had given us to him before creation began. And the Son has come, has taken our human nature, offered the obedience that we owed but failed to offer, offered himself as the sacrifice, and rose again. So, he came as the accomplisher of our redemption. The Father is the planner, the "purposer," the giver of the Son. The Son is the accomplisher of our salvation. And the Holy Spirit is the applier of our salvation. He's the one who brings our stony hearts to life, makes them tender to God's word, who gives us the ability to believe and trust in Christ and so to be united vitally to Christ. Peter speaks of this in the opening of his letter, 1 Peter 1, when he speaks of our being chosen according to the foreknowledge, that is, the advance love of God the Father, in the sanctification of the Spirit, to obey Christ and to be sprinkled with his redeeming blood. Paul in Ephesians 1 gives us even more detail in that glorious opening benediction from 1:3 to 14, speaking of the Father's choice of our being redeemed through the Beloved One, forgiven of our sins, and then being sealed by the Holy Spirit as the pledge, the down payment, the first installment of our final inheritance.
Answer by Dr. Dennis E. Johnson
Dr. Dennis Johnson is professor emeritus of practical theology at Westminster Seminary California, where he taught from 1982 to 2018. He previously pastored Orthodox Presbyterian churches in Fair Lawn, New Jersey, and East Los Angeles, California. Dr. Johnson was Associate Pastor of New Life Presbyterian Church (PCA) in Escondido. He served as moderator of the Orthodox Presbyterian Church General Assembly and Presbytery of Southern California, moderator of the South Coast Presbytery in the Presbyterian Church in America, member of the Orthodox Presbyterian Church Committee on Christian Education, and Trustee of Covenant College.