This is a question which arises regularly among those of religious faith. There are innumerable estimates and thoughts concerning it. Let us examine the facts that we can be assured are correct in discussing it.
 Can we know that young children go to heaven? Indeed we can. There are several scriptures which cannot be misunderstood unless some one is trying to do so. One of the earliest cases that we have written by inspiration was that of David when his baby born of his illicit affair with Bathsheba, died. David fasted and prayed while the child lay sick, but when he died, he arose and washed himself and ate. When asked by his servants why he did this, he gave this answer:
And he said, While the child was yet alive, I fasted and wept: for I said, Who can tell whether GOD will be gracious to me, that the child may live? But now he is dead, wherefore should I fast? can I bring him back again? I shall go to him, but he shall not return to me. (2 Samuel 12:22-23 KJV)
David knew that small children went to heaven. To read the full story of the child’s sickness and death along with David’s reaction, click here.
And another reason we can be assured of this is Jesus own words recorded by three of the inspired writers. “But Jesus said, Suffer little children, and forbid them not, to come unto me: for of such is the kingdom of heaven.” (Matthew 19:14, Mark 10:14, Luke 18:16 KJV)
Some would have you believe that children are born depraved and laden with sin. An argument which needs no time wasted on it. We are assured that children are not responsible for the sins of the parents. The prophet Ezekiel speaks plainly about that:
The soul that sinneth, it shall die. The son shall not bear the iniquity of the father, neither shall the father bear the iniquity of the son: the righteousness of the righteous shall be upon him, and the wickedness of the wicked shall be upon him. (Ezekiel 18:20 KJV)
 At what age does a person become accountable? There is no specific age and it is a waste of time to try and set one. A child can sin only when he becomes aware of what sin is. This varies widely with children due to their speed of maturing, their training, their environment and many other things. It becomes so involved that the human mind cannot know for certain. But the beauty of it is, God does know and he is fair. If parents fail to teach their children of God and the ways of biblical doctrines, the child may be considerably older before learning right from wrong. In such case, the parents will have sinned and perhaps the child has not, far longer than one raised by righteous parents who taught them from their formative years.
Sin is an infraction of the law of Jesus Christ. When a child reaches the point of maturity that he realizes a thing is sinful, yet he chooses to do or even wishes to do that sinful act, then he is accountable. Some may reach that level around ten years old, while perhaps more are twelve or even higher. The subject becomes quite confusing when all things are taken into consideration.
One of the requirements for becoming a Christian (a citizen of the spiritual kingdom of Jesus Christ, his church) is that of hearing and believing his word and that he is truly the Son of God.
If a child is too young to have learned that and believe it, then he cannot yet become a Christian. The scriptures give the steps into salvation clearly throughout the book of Acts.
The book of Acts of the Apostles has been referred to as “the book of conversions. One should study the book very closely and pattern his own life of leaving the sinful state and that of gaining entry into the Lord’s spiritual kingdom. The one he affirmed that he would establish in his conversation with his apostles…read this:
When Jesus came into the coasts of Caesarea Philippi, he asked his disciples, saying, Whom do men say that I the Son of man am? And they said, Some say that thou art John the Baptist: some, Elias; and others, Jeremias, or one of the prophets. He saith unto them, But whom say ye that I am? And Simon Peter answered and said, Thou art the Christ, the Son of the living God. And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven. And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven. (Matthew 16:13-19 KJV)
Now after his death and the arrival of the Holy Spirit which he had promised he would send to the apostles to ‘bring to their remembrance all he has said unto them’ and to ‘guide them into all truth’, which is recorded beginning with the first verse of the second chapter of Acts. The conversion of over 3,000 of the Jews were converted that very day. This was the very first ones to become accepted into the Lord’s kingdom. It was not yet come before this.
The next recorded conversions are in chapter 8 of Acts. The evangelist Philip went to Samaria and preached to them…their conversion is recorded from verses 5 through 12. Then, Simon, a sinful sorcerer was also baptized in verse 13.
From Samaria, Philip was called away by the spirit to go intercept an Ethiopian treasurer, a eunuch in charge of the treasury of Queen Candace of Ethiopia. Philip preached to him Jesus and he was converted and baptized.
We then have the conversion of Saul of Tarsus who was confronted on the road to Damascus by Jesus in a bright shining light in chapter nine. It was repeated twice more by Saul himself, whose name was changed to Paul, in chapters 22 and 26.
In Acts 10, the first gentile converts, Cornelius and his family were converted by Peter who was summoned to speak to him after an angel had appeared to him.
Then in Paul’s traveling, we read of Lydia and her household in chapter 16, the Philipian jailor also in chapter 16. Certain of the Athenians were also converted, although little is said about them.
Almost everywhere Paul preached a congregation of the Lord’s church was established. In Philippi, just mentioned, He continued on into Corinth in chapter 18 where many were added to the church, and Ephesus in chapter 19 where another group was established.
Here is a link which gives a brief coverage of those 11 conversions mentioned above. And of those 11 cases, 6 instances, believing is mentioned and is implied in the remaining 5. So it is of a certainty that for one to become a member of that kingdom, they must believe. They must learn of Jesus and the kingdom in order to believe. (Conversions in Acts)
Children who are unable to discern right from wrong are not fully accountable. Perhaps they understand a portion of God’s truths, and if so, they may be held accountable for those but not those which the do not understand.
Readers and interested scholars are urged to read the article linked above in order to gain a better insight into what the understanding is needed of the Christian.