Seeing as how you think Constantine's favourite civic should be serfdom, when in fact that system did not even exist until well after Constantine's time basically ends this discussion.
Anyways, the main point is.. we need El Cid! Spain desperately needs a second leader. And El Cid is amazing. Anyone read "The Poem of the Cid"? A great, fairly short read that depicts Cid as the epitome of chivalry and loyal vassalage. And I don't use the word epitome lightly! Awesome stuff.
Nope, incorrect. The name 'serfdom' itself is a later termology (although derived from the Latin servus meaning slave) , but Constantine developed the concept of the system and enforced it in the empire and although it can be argued that concepts of serfdom have been present in most societies since the appearance of structured chiefdoms, Constantine defined serfdom in his edicts of 332AD specifically addressing the concerns of tenant farmers..
Read any discussion of Early Medieval Europe and you will see that serfdom origins is the laws passed by Constantine, specifically those in 332AD that transformed free coloni into serfs. Their servile and bonded status was even referred to in the Constitution of 321AD.
The fundamental principle of serfdom, as alluded to in the Civilopedia, is that it implies that one group of people have the rights and powers to control the destiny of others, but unlike in slavery, the people being controlled agree to their servile position. In the emerging Byzantine social system it would be Constantines bonded coloni who would form the lowest class.
The Late Roman Empire faced declining birthrates and a shortage of labour. Successive administrations had tried to stabilise the situation by freezing the social structure of the rural provinces - crafts and trades were made hereditary, so that sons could not leave their professions for more lucrative jobs. Councillors were forbidden to resign and the coloni, cultivators of the agricultural land, were not to move from the demesne (the plot of land that is characteristic of the serf system) they were attached to (as in serfdom).
Indeed, former slaves and former free farmers were, by the laws and edicts of Constantine, made into a dependent class of the coloni (forming the lowest level of populace in the feudal system, apart from criminals).
Constantine passed a series of laws around 325 AD that only reinforced the servile position of the coloni, limited further their rights to free action outside of the demesne (as in serfdom).
With a declining birthrate and population, labor was the key factor of production. Successive administrations tried to stabilise the imperial economy by freezing the social structure into place: sons were to succeed their fathers in their trade. Councillors were forbidden to resign, and coloni, the cultivators of land, were not to move from the demesne they were attached to. They were on their way to becoming serfs. Several factors conspired to merge the status of former slaves and former free farmers into a dependent class of such coloni. Laws of Constantine I around 325 reenforced both the negative semi-servile status of the coloni and limited their rights to sue in the courts. Their numbers were augmented by barbarian foederati who were permitted to settle within the imperial boundaries.
Constantine demonstrated through numerous edicts and rulings that he was Therefore is it complete reasonable, and more historically correct, to say that Constantine's favour civic would be serfdom, rather than 'free religion' (which in itself is connected to liberalism - something completely at odds with the conservative nature of Byzantine politics).