In this article I intend to highlight the fact that ancient Christian inscriptions can help us just as much as the biblical and patristic evidence in revealing undeniable proof of the practice of baptism of babies and newborns respectively in the first centuries of the primary Church. We can find inscriptions that can be identified as being Christian since the end of the second century but it is only starting with the third century that the number of dated inscriptions became significant. Almost all early Christian inscriptions are epitaphs. After having presented some generalities about catacombs and the way that Christians were buried in the second and third centuries, I have translated from Latin and from Greek a series of inscriptions and I have annotated on them. The oldest epitaphs stand out due to their precision and their simplicity. Starting with the end of the second century the number of epitaphs has increased. It is a well-known fact that the Holy Sacrament of Baptism, the entrance and initiation in Christianity has been regarded as a mystery whose significance was not to be revealed to pagans or catechumens. Christians would not reveal the Holy Sacraments to those who hadn’t been baptised in order for them not to be desecrated.  For this reason, certain formulae have been used to make what was written on those inscriptions intelligible only to those initiated into Christianity. Thus, Christian symbols such as the fish that reminds us of Jesus, the anchor for hope, the dove as a symbol of the Holy Spirit and pure soul, the XP monogram, which was very popular in the fourth century, for Christ are to be noticed. The duration of life was engraved, years, months, days and sometimes information about Roman consuls who were leaders during those times. By reading them, we notice that the first Christians did not draw attention upon themselves and their achievements but upon God, upon the faith in Jesus Christ, and upon the hope for eternal life, heavenly peace, prayer for those who had been called by God and so on, this fact revealing their spiritual preoccupations and the fact that their most valuable possession was their faith in God and the prospect of life in Heaven.