The Christian life is like a car. One needs at least two important things to drive it: a key and fuel. When an individual comes to faith in Christ, he or she is given the key—salvation. But the car of the Christian life doesn't get very far without fuel—the divine enablement of the Holy Spirit, what the Bible calls being “filled with the Spirit” (Ephesians 5:18). Once we realize that we need to keep our spiritual tanks full every day, we'll live lives of true authenticity.