SALVATION BELONGS TO THE LORD
To say that we cooperate with God in any way in our salvation undermines the doctrine of salvation, robs our confidence in God, and tempts us to pride.
It is like the man who collapses from a massive heart attack and is rushed to the hospital. The doctor doesn’t ask, "Sir, would you accept my help to save you by performing heart surgery?" Nor does the doctor ask in the middle of the surgery, "Sir, I need you to cooperate with me a little here." No. The doctor is doing all of the saving, and the doctor gets all the credit for doing so. After the surgery the man can surely say, "Doc, you saved my life. I will be forever grateful."
This is exactly what Paul was saying in the passage, "And you He made alive who were dead in trespasses and sins" (Ephesians 2:1). This is what David meant when he said, "Salvation belongs to the LORD" (Psalm 3:8). And again this is what Solomon was saying in Proverbs: "The horse is prepared for the day of battle, but deliverance belongs to the LORD" (21:31).
To say that we are destined for salvation is not to say that we will try hard or choose well and therefore succeed to be saved. It means that God has miraculously brought us from death to life in Jesus. It means that we have nothing to boast of, nothing for which we deserve any credit. To God alone belongs all the glory (Psalm 115).