How do we know salvation is by God's will and not man's will?

The doctrine of salvation by God's will, rather than man's will, is paramount in Reformed theology. Romans 9:16 states, 'So then it depends not on human will or exertion, but on God, who has mercy.' This clearly delineates that God's election precedes human action and belief. Ephesians 1:4-5 further affirms that believers are chosen in Christ before the foundation of the world according to God's purpose and grace. This underscores the essential belief that it is God's will that brings about salvation and not any human effort or decision, which stands as a cornerstone of sovereign grace theology.