The statement that the document quoted, proclaimed the freedom of worship to all citizens of the Roman Empire.
Licinius (emperor of the West Roman Empire) and Constantine I The Great (emperor of the East Roman Empire) were colleagues as well as rivals, and together wrote the Edict of Milan, which proclaimed/granted the official toleration to Christians within the entire Roman Empire, and gave an end to persecutions organized and led by the authorities against specific religious groups (especially Christians).