The Scriptures are silent for the most part as to whether children have an age of accountability beyond which they are lost if no repentance occurs. David could speak with certainty of where his son would be (2 Samuel:12:23), and Paul spoke of the believing parent sanctifying the children (1 Corinthians:7:14). Jesus admonished His disciples to “suffer little children to come unto me, and forbid them not: for of such is the kingdom of heaven” (Luke:18:16–17). He spoke of the childlike attitude a believer was to have and left us with a strong implication that a sizeable portion of heaven’s population is made up of children (i.e., those who died as children).
"But Jesus called them unto him, and said, Suffer little children to come unto me, and forbid them not: for of such is the kingdom of God. Verily I say unto you, Whosoever shall not receive the kingdom of God as a little child shall in no wise enter therein."