Basically here's how it happens.
You encounter the statue, you can "use" it which will trigger the animation. The statue will say to keep your hands off from the holy statue of Vault Dweller's head. You will say that you are the Chosen One but the statue would not really believe it and say you are not. You however will say you are. And so for 12 hours, about which also indicates the message box. After that cutscene the statue says you have proven you are the Chosen One and gives you a magical rock, which he calls a souvenir. After that he says "Now get lost! Damn tourists..."