How do we know that God opens the door of faith?

The phrase 'opened the door of faith' in Acts 14 showcases God's sovereignty in the redemptive process. Throughout scripture, faith is presented as a divine gift, initiated by God's grace. The apostolic journey resulted not only in the introduction of the gospel to the Gentiles but also in individual hearts being opened to believe. This underscores the Reformed understanding that faith is not a human decision but a result of God's sovereign grace working within the hearts of people, similar to how God opened Lydia's heart in Ephesus.