Basis for the concept of an "Age of accountability" Having attended Baptist Churches for years, I've often heard the term "age of accountability" bandied about.

The idea is that if a child dies at a young age - before reaching the "age of accountability", that child will go to Heaven, because he or she is not yet responsible for his or her sins.  He or she is "too young to understand the Gospel".

This age is not a specific age, but is understood to be different for everyone.  I'm not asking what this age is.

What I am asking, is where is the Scriptural evidence to support such a doctrine?  

Quite frankly, one of the reasons I stick to Baptist Churches is not because I consider myself a Baptist, but because it's the one denomination where in my (admittedly limited) experience, Pastors consistently say "If I ever preach anything that's not in the Word, or contrary to the Word, don't believe me."

Yet, I can find no Scriptural evidence for such a doctrine.  Am I missing it?    If so, where is it in Scripture?  If it exists, please point me  to the verses.  

Or is it a doctrine based on supposition, attempting to reconcile the idea that a loving God, and the horrific idea that child could go to Hell simply for not being old enough to understand their lost state, repent, and put their faith in Christ?
There are two aspects to the Biblical basis for this doctrine.

1) Rationale

There is a rationale, theological argument that God is just, and would not impute sin where there was no knowledge of sin or no opportunity to choose Him.  This is based on Old Testament passages like Proverbs 24:12, as well as New Testament passages such as:


  sin is not imputed when there is no law -Romans 5:13


2) Precedence

But the main argument comes from a story in 2 Samuel 12:14-31 in which God takes the life of David's newborn son as punishment for his sin.  After his son is dead, David makes the following statement:


  But now he has died; why should I fast? Can I bring him back again? I will go to him, but he will not return to me.” -v.23


This is generally taken to mean that David expected to see his son again in Heaven some day, even though he died as an infant, and never had the chance to accept or reject God.

The obvious question though, is why did David expect to see his son again?  The popular answer, of course, is that all such children go to Heaven.  After all, the alternative is unthinkable - surely God would not judge an infant with eternity in Hell if they never had a chance to hear the gospel.

Assessment

For what it's worth, I think the doctrine of an "age of accountability" is based on a lot of misunderstandings and bad hermeneutics.  However, we can rest assured that God is perfect in His love, justice, and wisdom.  For an alternative view to the "age of accountability" see my post here.