God the Father initiates salvation, God the Son both validates it at the cross and demonstrates it in His life, but it is God the Spirit who activates salvation in the lives of the elect.
Or another way to put it is:
God the Father purposed and decreed to save an elect people, God the Son provided the sacrifice in order to make that salvation possible, yet it is God the Spirit who produces that salvation in the lives of His people.
Psalm 3:8 Salvation belongs to the LORD; may Your blessing be on Your people.
Psalm
37:39 The salvation of the righteous is from the Lord;
he is their stronghold in the time of trouble.
Psalm 68:20a He that is our God is the God of salvation.
Jonah 2:9b-Salvation belongs to the Lord!
Acts 4: 11-12, 11 This Jesus is the stone that was rejected by you, the builders, which has become the cornerstone. 12 And there is salvation in no one else, for there is no other name under heaven given among men by which we must be saved.”
Therefore, salvation is wholly and soley an act of God, humanity does not work alongside God in order to bring about their salvation, but God alone brings salvation into the hearts of His people, as He gives them a new heart that is ready to do His will in their lives.