Paul refers here to the connection of faith to salvation, which is a reminder of the doctrine of justification by faith. An understanding of the doctrine of justification is important for healthy Christian living. It is impossible to appreciate a Christian’s relationship with God apart from this doctrine.
Justification involves the imputation of the righteousness of Christ to each believer in him. His life of perfect obedience is imputed to each believer as his or her personal righteousness. Justification is a once-for-all divine act that never requires repetition.
This doctrine is one about which we should frequently meditate. Before we get up in the morning, say to yourself, ‘I am a person whom God has justified in his grace.’ Remind yourself that you are clothed in the righteousness of Christ.
This doctrine is liberty to Christians who despair about their sins. We know what it is like to regret our sins. But when we confess our sins, we discover that our standing cannot be changed, not even by our sinfulness. There is no condemnation to those who are in Christ Jesus.
The doctrine is also the launch-pad for Christian discipleship. There is a temptation to assume that we need little spiritual pushes along the way to help us ascend to God, such as prolonged times of prayer or occasions of spiritual enjoyment. These things are essential, but they are not to take the place of justification in our thinking. We are always tempted to legalism in the Christian life, that God will do more for us if we do more for him. Good works will follow regeneration, that is true. But the fact that God has made me right with him is the stimulus for discipleship.
And the doctrine is the basis of Christian assurance. It is the case that sanctification or the marks of grace enable us to deduce that we are Christians, but they are not to be the basis of our assurance. When we come to die, what will give us most comfort? The memories of spiritual highlights which came and went, or the permanent standing that we have through the work of Jesus? Obviously, it is the Saviour.