I was told recently that Constantine outlawed credobaptism, and that the practice of it and the refusal to baptize one’s children became punishable by death.
That would be highly unlikely since Constantine himself delayed his own baptism until he was on his deathbed.
Here's a snippet of what was going on in the Empire for a short period during Constantine's reign. (I uploaded the short chapter this was taken from as a PDF)
Perhaps more influential in the postponement of baptism, however, was the notion that the magical efficacy of the rite made it desirable to delay reception of the sacrament until such a time as it would have maximum effect. Once the rite became associated with the actual remission of sins, and was coupled with the unbiblical notion that post-baptismal sins could not be forgiven, it was only natural that people began to delay their baptisms until the last possible moment before death, if possible, or at least until some moment in time when the trials and temptations of youth had passed. The model for this behavior was Constantine himself, who delayed his own baptism until he was on his deathbed. But it also happened with some frequency in the case of both pagan converts and Christian parents who opted to delay baptizing their own children during this time period.
Thankfully, we have no problem in dating the period for which this tendency was prevalent in the church. While the seeds of this tendency pre-date the conversion of Constantine in 312, it does not appear to have been a widespread practice until after that time, coinciding, as we have already noted, with the influx of new converts into the church subsequent to that event. Furthermore, there is no particular case which may be cited for the practice of Christian parents postponing the baptism of their infant children prior to the year 329/30, when the later-to-be church father Gregory of Nazianzus was born.31
Gregory was one of a number of high profile church leaders in the latter half of the fourth century who reported that their own baptisms had been postponed by their Christian parents (the others being Basil the Great, Ambrose, Chrysostom, Jerome, and Augustine). But each of these men was born between the years 329 and 354. So the problem seems to have reached its acute stage during these first few decades after the conversion of the empire to Christianity.
This proposed dating is also supported by the fact that a new phenomenon arose in the middle of the fourth century—tombstone inscriptions which identify the dead persons as neophytes (newly baptized). The title was applied to both children and adults, and occurs only until around the year 400 with any regularity.
In fact, the written evidence is suggestive of a very short period of time during which this crisis played itself out within the church. According to Jeremias, after the year 365 the literary sources begin once more to cite infant baptism as the universal custom of the church, and to justify it theologically, as if nothing at all had happened.34 Even some of the very same theologians whose baptism had been delayed by their parents were arguing strenuously for the practice of infant baptism by the end of the century.35 The Pelagian controversy, which arose in the early years of the fifth century, put an end to the crisis once and for all.
Holstrom, B. (2008). Infant Baptism and the Silence of the New Testament (pp. 94–95). Greenville, SC; Belfast, Northern Ireland: Ambassador International.
