The principle of solidarity is clearly formulated in Mt 7,12. a text called "golden rule", where Jesus sums up the Old Testament with this phrase: "Everything you would want others to do for you, do it for them, because that means the Law and the Prophets". Jesus invites us to be supportive, or what is the same, to put ourselves in the place of the other, as if he were himself, doing with him what one would want them to do to him. For this we must renounce egocentrism; Each one must consider that others have a common destiny with him, and, therefore, deserve his attention and interest.

This principle of solidarity in its extreme formulation is expressed in the Gospel of Luke (6: 27-31): "Now you who listen to me say to you: Love your enemies, do good to those who hate you, bless those who curse you, pray for those who mistreat you. Whoever hits you on one cheek, also present the other; If you take off the cloak, also leave the tunic; to everyone who asks you, give it, and whoever takes your thing, do not claim it. That is, treat others as you want them to treat you. "