Now a certain woman named Lydia heard us. She was a seller of purple from the city of Thyatira, who worshiped God. The Lord opened her heart to heed the things spoken by Paul. Acts 16:14
Why must God “open a person’s heart” if they are to believe? Because we are all born sinners, who deny God. How does the Bible describe this condition?
Ephesians 2:1 & 5 And you He made alive, who were dead in trespasses and sins… even when we were dead in trespasses, made us alive together with Christ (by grace you have been saved).
Our spiritual problem is described as being “dead in trespasses and sins.” Not sick. Dead. Not dying. Dead. And dead people neither know they are dead, nor can they do anything about their condition. That is why if the dead are to ever be alive, someone else would have to make them alive. That someone is God, and that is exactly what God the Holy Spirit does when He “opens our hearts.” Ephesians 2:5 says He makes us alive. He raises the spiritually dead to life. And He does this unilaterally. Of course He does, because being dead, not only can we not raise ourselves, we cannot assist Him in raising us!
When He raises us from death to life, we are “born again.” Only then do we believe! We are not born again because we believe. We believe because we have been born again by the Spirit of God.
That is what happened to Lydia in Acts 16:14, and that is what happens to everyone who has ever, or will ever, be saved. Truly, salvation is of the Lord. Therefore, all glory be to Him forever and ever, Amen!