The innocence of children is a crucial doctrine. When the scripture says they ’are whole,’ that means that they are innocent—that they are alive in Christ.
Joseph Fielding Smith
"‘Little children are redeemed from the foundation of the world’ (DC 29:46)…when we come into this world, we come into it innocent as far as this world is concerned, just as we were innocent in the other world in the beginning. Every child-I don’t care where it is born; I don’t care what its color-that is born into this world comes into it innocent in its infant state.
“Why, when you look into the face of a little babe and he looks up and smiles at you, can you believe that that little child is tainted with any kind of sin that will deprive it of the presence of God should it die?” (Doctrines of Salvation, 2:51)
M. Russell Ballard
"In other words, we’re born good; we learn to sin as we grow older. And if you need evidence of the truth of that doctrine, please see your nearest infant. Look deeply into the child’s eyes. Have you ever seen such sweetness and purity? It‘s like you can look through a baby’s eyes right into heaven.
“Of course, that changes a little later in their lives when wide-eyed innocence turns into wild-eyed mischievousness. That’s when children become accountable and capable of sin—when they know and understand the difference between right and wrong. Through the Prophet Joseph Smith the Lord revealed that the age of accountability is eight years old. (see DC 68:25)” (Our Search For Happiness, p. 87)