Solidarity

Along with

•The Right to Life & the Dignity of the Human Person
•Call to Family, Community & Participation
•Rights & Responsibilities
•Option for the Poor & Vulnerable
•Dignity of Work & the Rights of Workers
•Caring for God's Creation

the United States Conference of Catholic Bishops explains that Solidarity is one of the seven key themes of Catholic Social Teaching:

“We are one human family, whatever our national, racial, ethnic, economic, and ideological differences. Our Catholic commitment to solidarity requires that we pursue justice, eliminate racism, end human trafficking, protect human rights, seek peace, and avoid the use of force except as a necessary last resort.”

As per Chapter 1 of the Vatican's Compendium of the Social Doctrine of the Church, “The universality and integrality of the salvation wrought by Christ makes indissoluble the link between the relationship that the person is called to have with God and the responsibility he has towards his neighbour in the concrete circumstances of history.”