What does it mean that God opened her heart? What does that have to do with salvation?
Acts 16:14—my translation and notes.
14 Then a woman named Lydia, a seller of purple from the city of Thyatira who worshiped God, listened to us. The Lord opened her heart, so that she paid attention to the things Paul was talking about.
[The Lord opened her heart is an important theological statement of soteriology (study of salvation). If God had not opened her heart, it would have never been open. God initiates salvation. No human can seek God (Romans 3:9-18), no one wants to. Our wills are bound and in slavery to sin (John 8:34, Romans 6:6, and Romans 6:16). God the Holy Spirit convicts people of their sin (John 16:7-13) and God the Father draws them to Himself by the force of love (John 6:44 and 1 John 4:19). God the Son draws all humans to Himself (John 12:32). God frees our will, opens our mind and heart (Acts 16:14, Luke 24:45, and Acts 26:18), and will save us from sin and its penalty if we put our faith and trust in God the Son, Jesus Christ alone (1 Peter 1:9, Romans 5:1, and John 1:12). Salvation is by grace alone through faith alone in Jesus Christ alone (Acts 4:12). Dr Harry Ironside has this insight: The very first evidence of awakening grace is dissatisfaction with one’s self and self-effort and a longing for deliverance from chains of sin that have bound the soul. To own frankly that I am lost and guilty is the prelude to life and peace. It is not a question of a certain depth of grief and sorrow, but simply the recognition and acknowledgment of need that lead one to turn to Christ for refuge. None can perish who put their trust in Him. His grace super abounds above all our sin, and His expiatory work on the cross is so infinitely precious to God that it fully meets all our uncleanness and guilt].