The biggest example of a judgment against unbelievers is Stephen's sermon in Acts 7. Facing the Sanhedrin, he uses some of the harshest language he can in condemning their actions:
You stiff-necked people, uncircumcised in heart and ears, you always resist the Holy Spirit. As your fathers did, so do you. Which of the prophets did your fathers not persecute? And they killed those who announced beforehand the coming of the Righteous One, whom you have now betrayed and murdered, you who received the law as delivered by angels and did not keep it (Acts 7:51-53).
Either Stephen was wrong to call out the priests or we are also called to be the witnesses of Christ, which must include telling others how they violate His law. Otherwise, why would they ever wish to..."
http://apologetics-notes.comereason.org/2014/10/are-we-not-to-judge-unbelievers.html?m=1
-vk-
