Solidarity is far more than a "feeling of vague compassion or shallow distress at the misfortunes of so many people, both near and far". It is a "firm and persevering determination to commit oneself to the common good. That is to say to the good of all and of each individual, because we are all really responsible for all".
Solidarity is key to the realization of the goals of Catholic social teaching. It is "a virtue directed par excellence to the common good, and is found in a commitment to the good of one's neighbour with the readiness, in the Gospel sense, to 'lose oneself' for the sake of the other instead of exploiting him, and to 'serve him' instead of oppressing him for one's own advantage (cf. Mt 10:40-42, 20:25; Mk 10:42-45; Lk 22:25-27)". It is the recognition and strengthening of the common ties that already exist between people. It is the realization that we are all debtors to the society in which we belong. We are the beneficiaries of a wealth of knowledge and culture, which we are obligated to maintain, increase, and pass on to those who follow us.
Our example here, of course, is Jesus:
The unsurpassed apex of the perspective indicated here is the life of Jesus of Nazareth, the New Man, who is one with humanity even to the point of "death on a cross" (Phil 2:8). In him it is always possible to recognize the living sign of that measureless and transcendent love of God-with-us, who takes on the infirmities of his people, walks with them, saves them and makes them one. In him and thanks to him, life in society too, despite all its contradictions and ambiguities, can be rediscovered as a place of life and hope, in that it is a sign of grace that is continuously offered to all and because it is an invitation to ever higher and more involved forms of sharing.Links
Jesus of Nazareth makes the connection between solidarity and charity shine brightly before all, illuminating the entire meaning of this connection: "In the light of faith, solidarity seeks to go beyond itself, to take on the specifically Christian dimensions of total gratuity, forgiveness and reconciliation. One's neighbour is then not only a human being with his or her own rights and a fundamental equality with everyone else, but becomes the living image of God the Father, redeemed by the blood of Jesus Christ and placed under the permanent action of the Holy Spirit. One's neighbour must therefore be loved, even if an enemy, with the same love with which the Lord loves him or her; and for that person's sake one must be ready for sacrifice, even the ultimate one: to lay down one's life for the brethren (cf. 1 Jn 3:16)".
Compendium of the Social Doctrine of the Church