Acts2:39, The promise is for
you and your children (present tense)and for all who are far off—
for all whom the Lord our God will call.” (future tense)
Well, take this into consideration. Have you ever seen a mother trying to discipline her 4-8 year old child at grocery store, church, or some type of function? The child then purposely ignores his/her mother, and then you see their father come around the corner and the child practically pees their pants? The father then gives them an instruction and they obey? I've seen that happen multiple upon multiple times.
Do children know good from wrong then, I would assume yes. There's something about their mother's instruction they purposely choose to ignore. They know they should listen, but they don't. Consider God's commandment of honoring your father and mother. Aren't children in direct violation of God's commandment? That is a sin.
I know what you're thinking, the child doesn't know he/she is disobeying God's commandment. I mean, I can understand your point. The child doesn't know they're disobeying God's commandment (committing sin), right? Well, here 's another situation. There's a 21 year old female that has never heard of God, and this female is involved in pornography.
Is this female guilty only of ignorance? Is she rendered sinless because of her lack of knowledge in an existent God and His commandments?
If the 4-8 year old child is sinless after disobeying their parents due to a lack of knowledge of God's word, the female pornography star is also rendered sinless. However, if the female pornography star is guilty of sin after she fornicates, even though she never heard of any God, the child is guilty of sin too.
God is no respecter of persons.
Also take into consideration, Lydia and her household were baptized (
Acts 16), the household of Stephanas was baptized (
1Corinthians 1), and the Jailer and his household were baptized (
Acts 16). I can only assume and say, one of these 3 families had to have a little child. To obey the gospel, you must acknowledge that you're a sinner.
I guess a child is born a sinner because of their condition, being estranged from God. If we were born sinless, God would never suggest of putting his law in our hearts. But our sinful actions are the nature (
Ephesians 2:3) of the heart we were born with.