Catholic social teaching includes all the Church beliefs and principles that have to do with society.
The starting point is the firmly held understanding that all people are created by God, and that they are capable of seeking and responding to God.
The Church teaches that humans were meant to live in society and not alone (see Genesis 2:18). The way we show our love for God is to love our neighbor (1 John 4:20).
Pope Leo XIII wrote that it was important that people understand that the Church does not teach that our relationship with God is distant, nor that it is purely spiritual; the things of this world and the details of our earthly lives matter a lot. (Rerum Novarum #42)
Much has been written before and since about the Church’s teachings about justice in society, and Pope Francis speaks frequently on these topics.