While you wrote this in regard to Acts 2:38+ I don’t find support for your baby assertion.
Act 2:38 Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
Act 2:39 For the promise is unto you, and to your children, and to all that are afar off, [even] as many as the Lord our God shall call.
Act 2:40 And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation.
Act 2:41 Then they that gladly received his word were baptized: and the same day there were added [unto them] about three thousand souls.
Same word in the interlinear:
(Greek/English Interlinear (tr) NT) Acts 2:39 umin <5213> {TO YOU} gar <1063> {FOR} estin <2076> (5748) {IS} h <3588> {THE} epaggelia <1860> {PROMISE} kai <2532> {AND} toiV <3588> {TO} teknoiV <5043> {YOUR} umwn <5216> {
CHILDREN,} kai <2532> {AND} pasin <3956> {TO ALL} toiV <3588> {THOSE} eiV <1519> {AT} makran <3112> {A DISTANCE,} osouV <3745> an <302> {AS MANY AS} proskaleshtai <4341> (5667) {MAY CALL} kurioV <2962> o <3588> {[THE] LORD} qeoV <2316> hmwn <2257> {OUR GOD.}
When I was baptized a few young men of maybe 8 or 9 that I would characterize as children had made a decision for Christ and were being baptized as well.
Strong’s
** children**
New Testament Greek Definition:
5043** teknon {tek’-non}**
from the base of 5098; TDNT - 5:636,759; n n
AV - child 77, son 21, daughter 1; 99
- offspring, children
1a) child
1a) a male child, a son
1b) metaph.
1b1) the name transferred to that intimate and reciprocal
relationship formed between men by the bonds of love,
friendship, trust, just as between parents and children
1b2) in affectionate address, such as patrons, helpers,
teachers and the like employ: my child
1b3) in the NT, pupils or disciples are called children of
their teachers, because the latter by their instruction
nourish the minds of their pupils and mould their
characters
1b4) children of God: in the OT of “the people of Israel” as
especially dear to God, in the NT, in Paul’s writings, all
who are led by the Spirit of God and thus closely related
to God
1b5) children of the devil: those who in thought and action are
prompted by the devil, and so reflect his character
1c) metaph.
1c1) of anything who depends upon it, is possessed by a
desire or affection for it, is addicted to it
1c2) one who is liable to any fate
1c2a) thus children of a city: it citizens and inhabitants
1c3) the votaries of wisdom, those souls who have, as it
were, been nurtured and moulded by wisdom
1c4) cursed children, exposed to a curse and doomed to God’s
wrath or penalty