have all the answers
To be able to provide information about any given topic, or reliable advice about life in general. Why are you asking me about the afterlife? It's not like I have all the answers! I'm here because I'm going to fail biology, and you always have all the answers.
have/know all the ˈanswers
be or seem to be more intelligent or know more than others: He’s an economist who thinks he knows all the answers.