via the Vatican:

No matter how ancient or widespread, Cain’s violence cannot be tolerated as “normal.” On the contrary, the norm is revealed in God’s question to the guilty party: “Where is your brother?” (Gen 4:9). It is in this question that we find our vocation, the rule and measure of justice….

Brother, sister, where are you among the migrants who are despised, imprisoned and rejected, among those who seek salvation and hope but find walls and indifference? Where are you, brother, sister, when the poor are blamed for their poverty, forgotten and discarded, in a world that values profit more than people? Brother, sister, where are you in a hyper-connected life where loneliness corrodes social bonds and makes us strangers even to ourselves?…

Recognizing that the other person is a brother or sister means freeing ourselves from the pretense of believing that we are isolated individuals or from the logic of forming relationships only out of self-interest. It is not only self-interest that makes us enter into relationships. Great spiritual traditions and the maturation of critical thinking enable us to go beyond blood or ethnic ties, beyond those kinships that recognize only those who are similar and reject those who are different. It is interesting that in the Bible, as revealed by scientific exegesis, it is the most recent and mature texts that narrate a fraternity that transcends the ethnic boundaries of God’s people and is founded on a common humanity. The stories of creation and the genealogies bear witness that all peoples, even enemies, have the same origin, and the Earth, with its goods, is for everyone, not just for some….

Fraternity is the most authentic name for closeness. It means rediscovering the face of the other. For those who believe, they recognize the Mystery: the very image of God in the face of the poor, the refugee and even the adversary.