One who heard us was a woman named Lydia, from the city of Thyatira, a seller of purple goods, who was a worshiper of God. The Lord opened her heart to pay attention to what was said by Paul. (Acts 16:14)
Everywhere Paul preached some believed and some did not. How are we to understand why some of those who are “dead in trespasses and sins” (Ephesians 2:1, 5) believed and some did not?
The answer why some did not believe is that they “thrust it aside” (Acts 13:46) because the message of the gospel was “folly to them, and they [were] not able to understand” (1 Corinthians 2:14). The mind of the flesh “is hostile to God, for it does not submit to God's law; indeed, it cannot” (Romans 8:7).
Those who hear and reject the gospel “hate the light” and do not come to the light lest their deeds should be exposed (John 3:20). They remain “darkened in their understanding . . . because of the ignorance that is in them, due to their hardness of heart” (Ephesians 4:18). It is a guilty ignorance. The truth is available. But “by their unrighteousness they suppress the truth” (Romans 1:18).
But why then do some believe, since all are in this condition of rebellious hardness of heart, dead in our trespasses? The book of Acts gives the answer in at least three different ways. One is that they are appointed to believe. When Paul preached in Antioch of Pisidia, the Gentiles rejoiced and “as many as were appointed to eternal life believed” (Acts 13:48).
Another way of answering why some believe is that God granted repentance. When the saints in Jerusalem heard that Gentiles were responding to the gospel and not just Jews, they said, “Then to the Gentiles also God has granted repentance that leads to life” (Acts 11:18).
But the clearest answer in Acts to the question why a person believes the gospel is that God opens the heart. Lydia is the best example. Why did she believe? Acts 16:14 says, “The Lord opened her heart to pay attention to what was said by Paul.”