See also Catechism 153-165, 179-180, 183-184.
The Compendium notes seven characteristics of faith. Faith is: (1) necessary for salvation, (2) a free gift, a grace, (3) a human act, (4) it is certain, (5) it works through charity, (6) it continually grows, and (7) it is a foretaste of heaven. (We note an eighth characteristic of faith as well.)
1. Faith is ... necessary for salvation
If salvation was not necessary, we would not need faith, since we would already be living in perfect friendship with God, enjoying whatever God revealed of the divine glory to us. We would not be on a journey from separation towards union. Yet since we do need to be saved, to walk the path from separation to reunion, we discover that faith has the effect of guiding us on this way.
It is God, revealed in Jesus Christ, who is the light we walk towards, leading us home.
Faith is the gift of sight which enables us to see that light. Without the light of faith we would be lost. This light of faith is a special divine gift, a grace, and it is meant to complement and complete the gift of reason, which by contrast has a natural character. It is reason that enables us to have the dignity of cooperating in our own salvation.
In the order of creation the gift of God's love invites a human response of love. In the order of salvation the gift of the saving grace of God invites the response of human cooperation through works that develop and heal creation through that grace.
2. Faith is ... a free gift, a grace
Since God wants our cooperation, we need to use our reason to work out how to respond in practice to the gift of grace. God does not give us a daily list of chores, but by prompting us with grace draws out from us a response in accord with our natural gifts.
This is a close and continuous process, yet our lack of spiritual awareness can make it seem that God left some general instructions for us, and then went away, leaving us to it.
This mentality replicates in our minds the separation from God which faith is meant to overcome. So the light of faith seems dim and a long way off, hidden over the horizon somewhere. This lessening of faith leads to a weakening of hope, because we are in encroaching darkness, and the way ahead is uncertain.
3. Faith is ... a human act
Because of this potential loss of hope we need a certitude of faith. The light of faith will always seem to flicker and be in danger of going out if we rely only on our understanding of the faith. Even when we are in periods of temporary darkness, we need the certainty that the light is still there, otherwise we will despair of finding our way out.
God gave the certainty of faith to the Church, not to individuals regardless of whether they are separated from the Church or not.
Each person will individually have the light of faith if he or she stays within the community of light.
Although faith is offered to us as a gift, in order to accept that gift we need to make a decision to accept it. This decision is a human act, and faith passes by way of this act. If faith is offered to us it only enters into us and changes us if we accept it.
4. Faith is ... certain
The light of faith is one light, the light of Christ, and the Church is one because it abides in the one light. Separation from the Church is separation from the certitude of faith.
If we do not have the certainty of faith we will seek some other kind of certainty, and trust more in the judgement of our own reason, or of those we follow, than in the one faith.
5. Faith ... works through charity
It is only possible for people to be truly united through charity, through love. Love is the sign that faith is working. This is why the Church is meant to be a community of love.
We could say that ‘faith is what love looks like from a distance’, hence it appears as light.
Once we arrive in the light, we find the love convincing, because we feel its warmth, and do not need further reasons. To the extent that this becomes real in the Church, people will see the light from far off and believe that it is worth heading in this direction. While we are still on the journey we need faith, because Love has not yet fully penetrated to every corner.
6. Faith ... continually grows
The nature of love is to grow. Since God is love, there is no end to the forms of love God can give.
So we know something is not love if it has stopped growing, if nothing is flowing over the sides, if the light is diminishing.
We are continually tempted to say, ‘That is enough’. If the love diminishes, the light dims. If the Church's light dims, how will people know which way to go to find Christ?
7. Faith is ... a foretaste of heaven
Faith is a foretaste of heaven. The heavenly city is the light over the horizon, the ultimate reunion with God. How can faith be a foretaste of this? Because the Church carries the light of Christ on her journey.
The light we can dimly see from over the horizon is the same light that lights the Church's way on her journey of faith.
Jesus Christ is the light which has come into the world. Believing in him gives us access to the light that beckons from over the horizon. He has come to guide us home, accompanying us on every step of the journey. When we arrive at the heavenly city we will not be strangers, because we already know the one who awaits us. As the distance narrows, faith is revealed more and more as love. The one we have come gradually to know through faith is the same one whose Love casts the light.
8. Faith ... journeys through darkness
Because evil darkens the world, Jesus leads the Church through the darkness to find those who are lost. If we resent these ‘detours’ it means we have not learnt the lesson that faith works through love. Jesus is the Good Shepherd. But he does not want to have to do the shepherding on his own. The Church too must be a shepherd, and especially those who help Christ lead the Church on her journey.
We must go with Jesus seemingly out of the light and into the darkness, to share the light with others.
The Church also must pass through Holy Saturday to the glory of Easter. God wants our cooperation with the gift of faith most deeply of all to lead everyone home.
You might also like to read The Solution to the Problem with the Solution: What Kind of Thing Is Christianity?