This can be stated in active form. Alternate translation: "those people whom others treat unfairly" (See: [[rc://en/ta/man/translate/figs-activepassive]])
Here "kingdom of heaven" refers to God's rule as king. This phrase is only in the book of Matthew. If possible, keep "heaven" in your translation. See how you translated this in [Matthew 5:3](./03.md). Alternate translation: "for God in heaven will be their king" (See: [[rc://en/ta/man/translate/figs-metonymy]])