Schaff, Philip. History of the Christian Church (The Complete Eight Volumes in One). Amazon Kindle Edition, 2014.
Volume 2, Ante-Nicene Christianity A.D. 100-325, “Chapter 5. Christian Worship” (Includes an introduction and sections 59-74).
§73. Infant Baptism.
Schaff observes that the earliest days of Christianity, with a large amount of missionary activity and many adult converts, had an emphasis on baptism of adults. As the church became more established and accepted within the state, there was more emphasis on infant baptism (Schaff 2014, Loc. 15508). Prior to the reign of Justinian there were no legal requirements for baptism. Many children of at least one Christian parent were not baptized until adulthood. However, it was not uncommon, even in the apostolic period, for children of converts to be baptized (Schaff 2014, Loc. 15519). Schaff goes on to give many examples of the baptism of very young children. Baptismal regeneration is thus affirmed. “ moral and spiritual regeneration, as distinct from sacramental, would imply conversion, and this is a conscious act of the will, an exercise of repentance and faith, of which the infant is not capable” (Schaff 2014, Loc. 15535). Tertullian was known to suggest delaying baptism but not to object to the sacramental effects or to its apostolic origin (Schaff 2014, Loc. 15541).