Their coming to faith was a result of the revelation of the gospel. This gospel broke the darkness that had led them to believe all sorts of deception all their lives, and it turned them to the true life that was in Christ Jesus. Previously they had witnessed great magical performances of Simon the magician, and still continued to live in bondage to sin and death. But this time, they experienced the power of God in their lives.
12 But when they believed Philip as he preached good news about the kingdom of God and the name of Jesus Christ, they were baptized, both men and women.