Plenty of people claim to heart God speaking to them. Maybe some of them are right, but there's no way to distinguish such people from the ones that are lying or suffering from a mental illness.
Mohammed, after all, believed that God dictated the Koran to him.
Your position has nothing to go off except some rock in a lab that magically tell you how old they are.
It's amazing how many creationists are willing to dismiss and belittle the the fruits of Western scientific progress.
"Amazing" is one word for it.