That question was asked of Jesus Christ by Pontious Pilate. A similar exchange occured this past week between David Horowitz and Ward Churchill in a debate. The ethics professor from Colorado U attempted to establish that there is no truth, just consensus about what it is. The communist/self described socialist did not dispute David's fact that 120,000,000 people were killed in the communist experiment; 60,000,000 of them by intentional starvation.
He would not dispute that there were three people on the stage that day, or that he is paid money from Colorado U. There are many examples of liars.
Either you tell The Truth or not. If you wish to pass on a question, that is all right. Not everyone deserves to hear the truth, and some do not know what it is. I feel sorry for them.