How are Christians supposed to tell the truth if we aren’t supposed to judge? Simple, judge. By telling the truth you are judging people. Christians are not to condemn people but we are to tell them the truth. That means you tell them that they did something wrong but you don’t say that they will be punished for it.
John 3:17 “For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him” Besides Jesus being crucified, it also means he told the truth. He told a guy that he would have to follow him and not bury his dead for “the dead will bury the dead” He said the truth, he didn’t condemn him. When David committed adultery and then murdered his best friend, the prophet went to him and told him the truth. He didn’t condemn him. He told him what he did wrong. Should Christians judge people on the way they look, their sexual preference, what race they are, or how they speak? No, but we should judge what really matters.