I will take this opportunity to respond to Amy G., whom I was replying to as well when the thread closed.
This is a ridiculous statement. First, I didn't say people aren't born with a sin nature. I can't speak for anyone else, as it's a long thread, but I've not read anything to that effect.
Secondly, being born with a sin nature does not negate an "age of accountability" which is what Winman and I are talking about. As with other doctrines like the Doctrine of the Trinity, which is not specifically spelled out, there is an age of accountability that, though not specifically spelled out, is established in biblical writings.
People are accountable for their response to the witness of God in creation -- as Paul's excellent treatise in Romans 1:18-32 establishes -- and also to the witness of God in the Bible and in the person of Christ.
Acts 17, NASB
30 "Therefore having overlooked the times of ignorance, God is now declaring to men that all people everywhere should repent,
31 because He has fixed a day in which He will judge the world in righteousness through a Man whom He has appointed, having furnished proof to all men by raising Him from the dead."
But second, since that response is based on one’s ability to comprehend and respond to the message, a person becomes personally accountable when he or she reaches a point where they have the spiritual and mental faculty to grasp the issues. This does not mean they are not sinful, it does not mean they do not have a sin nature with which they were born. It only means that they have not reached a place where they can understand.
Children reach an age of knowing right from wrong much earlier than they learn and can conceive of the need for a Savior who is Christ the Lord. Around four, five, or six years of age, children know what behaviors are expected of them and what behaviors will get them in trouble with mom, dad, grandparents, brothers, sisters, sitters, teachers, etc. Knowing there is no hope for them to escape the inherent nature within them without Christ is still years away.
My own kids committed to Christ at the age of eight. I know of children who made that decision even earlier, though I'm not convinced anyone younger than nine or ten, frankly, is fully capable of comprehending the need for Jesus Christ in their lives, and I believe more are much older. The Jewish age of accountability -- when a boy becomes a man and a girl a woman -- is 13. Like the biblical age of leadership being established at 30 years, I believe that "age of accountability" as traditionally held by the Hebrews is very accurate, though maturity comes still later in life. There has to be a level of understanding, an ability to be convicted of sin, before one can make a decision for Christ. So this "age of accountability" has a two-fold aspect: Knowing right from wrong, and knowing there is nothing we can do about it.
While having the first without knowledge of the second may not make one accountable, it does make one feel guilty. That is when the search begins for righteousness, though of course no one that young understands that word. But it is, nonetheless, what they are looking for, and will continue to seek. When they realize there is something specific to be seeking, that is when they have become accountable.