How do we know that God opens hearts for salvation?

The act of God opening hearts for salvation is vividly illustrated in the account of Lydia in Acts 16:14, where it states, 'The Lord opened her heart to pay attention to what was said by Paul.' This emphasizes the Reformed understanding that before any person can respond to the gospel, a divine act of regeneration must occur. It is not through human effort but by God's sovereign grace that individuals come to faith. This notion is echoed in Ephesians 2:8-9, which teaches that by grace we are saved through faith, and this is not our own doing; it is the gift of God. Therefore, the artwork of salvation is done entirely by God, who chooses whom He wills.