The Westminister Confession of Faith in Plain Language1. The faith that saves the elect is itself a free gift from God. The Holy Spirit works in hearts through the ministry of the Word to produce this faith. It is made even stronger by participating in the sacraments, praying, and hearing the preaching of the Word of God.
2. This faith enables Christians to believe everything God reveals in his Word. They trust that God himself speaks with his full authority in the Scriptures, and they respond appropriately to what he says—when the Bible demands obedience, they obey; when it warns that sin will be punished, they tremble; and when it makes promises about this life and the next, they embrace those promises wholeheartedly. But true saving faith mainly involves this: Christians must accept, receive, and rest upon Christ alone for justification, sanctification, and eternal life because God has promised these things through his grace.
3. Sometimes faith can be strong, and at other times it can be frail. But even though it can be attacked and weakened, it will always win the battle. Most Christians will continue to grow in their faith until they are absolutely certain that they are saved through Christ. Christ was the one who gave them their faith in the first place, and he will make sure it wins out at the very end.