One distinct feature of Christianity, it is the personal faith demanded from all humans, and the voluntary submission to God’s will through that faith placed on Jesus as the Son of God and Saviour of all humanity.
There is not ground to support infant baptism in the Scripture. All of the sections that deal with this sacrament, as well as with the Lord’s Supper; personal faith it is assumed from the recipients (Mark 16:16), and we are told that without faith, “we cannot please God” (Hebrews 11:6).
However, infants were commenced to be baptized after the apostolic era, under the belief that through the consecrated water of baptism, a newly born would be saved from Original Sin, thus ensuring their ‘salvation’, and Holy Communion given to them as a consequence, custom that was changed later in the West to a more conscious age.
But however these and other things were done, even in the case of some people believing in gracious justification of a newly baptized baby; all agreed that this baptism, compared by many back then and even today to the old Circumcision, could only be ‘owned’ by a Christian when arriving to a conscious age, he or she assented to their childhood sacraments, and thus, becoming fruitful. So, in practice, Personal Faith, was awaited and required from all believers, since OT days to these Christian days, to be truly consider ‘justified’, and the rightful owner of sacramental life.
Justification by Faith has always been the required element that has saved humans since Adam’s fall. Even when the Law was given, it was given in full knowledge that it was impossible to be maintained to perfection, as the Law itself demanded (Galatians 2:16; 3:11); but it was given to us by God anyway, to convinced us of our sinfulness and bring us to the Cross of Jesus (Romans 3:20). This way, all saved ones from the times of creation until the last man to be born yet, are saved by Faith in Jesus, and repentance and submission to his will. (Hebrews 11:2).
But salvific faith, it is not just a concept, or an ideal, a mental assent of a truth; but it must come with a resolution to renounce to our old lives and embrace a totally new life in obedience to God for eternity. This repentance and obedience are the marks of the true salvific faith, and not the mental assent of false disciples of Christ, who like the demons, know God, but do not submit to his will, neither regret their old lives (James 2:19).
This is the faith that it is required from all humans to be saved, and without it, salvation is impossible, save in the case of the mentally disabled, infants and stillborn.
Christianity does not have grandchildren, neither considers lineage legacy, but demands, as the last form of revelation, an active submissive, obedient faith from every human, to be able to produce fruits of salvation.
“Without faith it is impossible to please God, …”