Nowhere in scripture will you find the command: “Go ye into all the world and be nice.”
Christian niceness is neither Christian nor nice, just like Grape Nuts is neither grape nor nuts. Jesus was direct. He showed no hint of vague, spineless, “I don’t want to hurt your feelings,” niceness. To the woman caught in adultery, he said she had sinned. Black and white. Clear. Unambiguous.
Jesus also spoke with grace. He said to the same woman, “Neither do I condemn you.”