I wholeheartedly believe that God is able to bring about true repentance and belief in young children. Pastor Dennis Gundersen believes this, too. But he also wants to caution us and point out some important realities, especially regarding children growing up in Christian homes:
How common will it be to hear a profession [of faith] from a child who is being reared in a Christian home, especially in a home where biblical instruction and exemplary godly faith is presented to him frequently, perhaps even daily, God giving your family grace! Should we then actually be surprised to hear him say that he believes the things his parents believe?...
In such a family climate, can it then be considered a remarkable thing that a child says he believes the gospel which has been held before him and taught to him for so long, in so many ways and with so many appealing evidences of its power? I think we would be shocked if he were to say that he did not believe it…So, it would be foolish to conclude that a child is saved merely because he makes the bare acknowledgement that these things are true.
Please then, parents: be wise enough to not speak assurances about eternal safety to your child’s soul based on such shallow grounds. Love your child enough to not be a misleading messenger to him, in ways that you would never mislead another adult professing the same beliefs. Is this not the most common deception, after all, among adults and children alike?—to presume that because I know and believe these facts, that I am saved. How many are among those multitudes who are presuming that a mere acknowledgement of the gospel, which never affects the heart and life, is enough? And of all persons, a child is perhaps the least equipped to know his own heart in this matter. Don’t help him fool himself.
(Your Child’s Profession of Faith, pp. 51-53)
Along with this book, here are three more resources that I highly recommend to both parents and teachers:
Helping Children to Understand the Gospel (Truth78)—In Part 1, Sally Michael provides very helpful insights for discerning the true spiritual condition of children at various ages, including very young children.
Established in the Faith: A Discipleship Guide for Discerning and Affirming a Young Person's Faith (David Michael)—This is especially suited for older children and teens.