The relationship between this edict and the better known settlement of 313 is often reversed in popular accounts. Serdica came first and did the legally decisive thing: it converted Christianity from a proscribed practice into a permitted one across the eastern provinces where the persecution had been fiercest. What Constantine and Licinius agreed at Milan two years later went further in two respects. It extended a general freedom of religion to everyone rather than an indulgence to one group, and it ordered the restitution of confiscated property, including places of assembly, at public expense where a purchaser had to be compensated.
Serdica's own protection was also short lived in the east. Maximinus Daia, who governed the eastern provinces, published the edict but resumed pressure on Christians within a year through petitions from cities asking that they be excluded, a device that let him answer requests rather than issue orders. That renewed persecution ran until his defeat by Licinius in 313.
The text survives in two places, both partisan and both indispensable: in Latin in Lactantius, who wrote a polemic on the deaths of the persecutors, and in Greek in Eusebius, who included it in his church history. There is no independent copy, no inscription and no papyrus. That the wording rests entirely on Christian transmission is a fact worth keeping in view when reading its concessive phrasing.