The Word of God clearly teaches that those very children can also fall away from God.
Matt 24 24 For false messiahs and false prophets will appear and produce great signs and wonders, to lead astray, if possible, even the elect.
1 Tim 4 1 But the Spirit explicitly says that in later times some will fall away from the faith, paying attention to deceitful spirits and doctrines of demons,
Heb 6 4 For it is impossible to restore again to repentance those who have once been enlightened and have tasted the heavenly gift and have shared in the Holy Spirit 5 and have tasted the good word of God and the powers of the age to come 6 and then have fallen away, since they are crucifying again the Son of God to their own harm and are holding him up to contempt.