R.J. Rushdoony was writing about “social justice” decades ago, before most of us had ever heard of it. Here’s one of his essays on the subject, recently re-published. You’ll find it hasn’t aged a bit.
https://chalcedon.edu/resources/articles/social-justice
Simply speaking, Rushdoony explained that “social justice” differs from God’s justice because it’s made up by self-anointed intellectuals. It is whatever they say it is, from day to day. It could hardly have helped falling into the arms of postmodernism, which spurns day-to-day reality and goes so far as to say everything is just made up.
But because it’s the product of humanist fat-heads, “social justice” can never be true justice. Only God’s justice can be that. Only God’s law is immutable. Intellectuals’ laws are subject to sudden change. That’s what makes them so hard to live with.
Humanism has a lot to answer for.