No one in the country may legally operate a motor vehicle without said vehicle being properly registered and licensed. Also, no one may operate a motor vehicle legally without testing to demonstrate basic knowledge of traffic laws and a basic ability to drive safely. This is because it is clearly in the interest of society to protect the populace at large.
Since firearms are Clearly dangerous in untrained and unlicensed hands, just as a motor vehicle, it is therefore reasonable for citizens and their minor children to also be required to be trained in firearms safety and use before being able to purchase, own, rent or use firearms.
This is not a limitation on the right to bear arms, but rather a limitation on recklessness and stupidity.
Driver's Ed and Hunter's Ed, anyone?