This great work of salvation is the work of God alone. It was planned by God, purchased by God, produced by God, is preserved by God, and shall be perfected by God. From start to finish, "Salvation is of the Lord!" Therefore God alone shall have the praise for it. God's work of grace that is called "salvation" must be understood as a work consisting of three things.
Salvation is what God has done for us in Christ. In eternity, before the worlds were made, the Lord God loved us, chose us, predestinated us to be his own, adopted us, accepted us, and blessed us in Christ (Eph. 1:3-6). Our salvation was arranged and accomplished in that covenant of grace ordered in all things and sure made between the three Persons of the holy Trinity before the world began. In that everlasting covenant, God the Father became our Father, God the Son became our Surety, and God the Spirit became our Sanctifier. In time, our salvation was obtained by the obedience of Christ as our Substitute. We have been forgiven, justified, and sanctified by the merits of his righteousness and shed blood.
Salvation is also what God has done and is doing in us. We were dead. He made us alive (Eph. 2:1-4). He made us new creatures in Christ. He gave us a new heart, a new will, and a new nature in sovereign regeneration. He produced repentance and faith in us (Eph. 2:8-10). He is working in us to will and to do of his good pleasure (Phil. 2:13) and preserving us in life and grace by his almighty power (II Pet. 1:5).
And salvation is what God shall do with us. When the Lord God is finished with us, when our salvation is complete, we will be exactly conformed to the image of Christ (Rom. 8:29). And he shall at last present us faultless before his throne and in the ages to come shall "show the exceeding riches of his grace in his kindness toward us through Christ Jesus" (Eph. 2:7).