In your article about miscarriage, you wrote, “The Bible says life begins at conception (Psalm 139:13-14) and children under the age of understanding have eternal life (Romans 7:9).” I fail to understand how Romans 7:9 has anything to say about the age of children, or their understanding. Please explain.
The general context of Romans 7 is Paul’s claim that rather than save him, the Law exposed the extent of man’s sinfulness, condemning him to death. Being a Jew who was obviously alive at the time, he wrote, “For I was alive without the law once: but when the commandment came, sin revived, and I died” (Romans 7:9). (The word for “without” also means “apart from”.) Since he was physically alive he had to have been referring to spiritual, or eternal life. In Judaism children are not accountable under the Law, therefore their sins are not counted against them. They have eternal life.
When they reach the age of accountability, they become responsible for their sins. They acknowledge their accountability in a ceremony called bat mitzvah for girls, usually held at age 12, and bar mitzvah for boys age 13. This is what Paul meant by saying, “The commandment came, sin revived, and I died.” So as soon as Paul became old enough to be accountable for his sins, he was scheduled for death, already as good as dead.
No official written references to the method for conducting bar or bat mitzvah ceremonies existed during Paul’s time. But the practice was obviously well known enough that Paul could expect even his gentile readers to understand what he was talking about. Since Paul was adamantly opposed to following tradition for its own sake, he must have known that belief in an age of accountability was legitimate from God’s perspective.
The age at which a child becomes accountable has to do more with attaining the intellectual ability to understand the sin/ salvation issue than reaching a certain age and that’s why it’s not specified in the Bible.