...is that’s what the earliest Christians did.
St. Polycarp was given a chance to renounce his faith
or be killed around 155 AD. He is quoted as responding he had followed
Christ for 86 years and wasn’t about to stop now; he was 86 years old.
He clearly considered himself to be a follower of Christ from his
infancy; something he would’ve associated with baptism.
Irenaeus and Origin state plainly in their writings that infants are
baptized and Hippolytus in 215 AD wrote “And they shall baptize the
little children first. And if they can answer for themselves, let them
answer. But if they cannot, let their parents answer or someone from
their family.” which gives a nice description of not only infant baptism
but God parents as well. We could list many, many more but
interestingly absolutely no record is found of early Christians writing
that infants should not be baptized.
That those who were taught
directly by the apostles and biblical authors baptized infants is yet
another reason that Catholics do today.