They listen to preaching, read the Bible or other books or they can seek the Truth or be inspired by God. Very few are struck down by Jesus like St Paul. And perhaps there more ways to learn to believe.
Believing is a process and we grow in our belief and love of God.
For children, including infants, it is the parent’s responsibility to teach their children about God and they too can grow in their belief in God. Or they can reject a belief in God
You are talking about an intellectual belief...That's not the belief of salvation...Belief in God/Jesus is not a lifelong endeavor...It's a one time deal...Belief in Jesus is a trust that you know he is your Saviour and will get you to heaven...
Psa 84:12 O LORD of hosts, blessed is the man that trusteth in thee.
Isa 12:2 Behold, God is my salvation; I will trust, and not be afraid: for the LORD JEHOVAH is my strength and my song; he also is become my salvation.
Act 16:30 And brought them out, and said, Sirs, what must I do to be saved?
Act 16:31 And they said, Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house.
Act 16:32 And they spake unto him the word of the Lord, and to all that were in his house.
Act 16:33 And he took them the same hour of the night, and washed their stripes; and was baptized, he and all his, straightway.
Act 16:34 And when he had brought them into his house, he set meat before them, and rejoiced, believing in God with all his house.
Believe
πιστεύω
pisteuō pist-yoo'-o
From G4102; to have faith (in, upon, or with respect to, a person or thing), that is, credit; by implication to entrust (especially one’s spiritual well being to Christ): - believe (-r), commit (to trust), put in trust with.
For infants, they do not have personal sins, yet they receive forgiveness of original sin passed down from Adam.
So what, do they get their original sin back when they are a little older, when the men have to toil to make a living and the women go thru pain during childbirth???
Original sin is never taught in Scripture.
It’s a made up concept by the Catholic church for which they then created the solution, water baptism.
Nice racket there.