The "slander" is a false, false understanding, perversion, and spreading of God's Word: the Scriptures of the Prophets, the Teachings of Jesus Christ and the Apostles about the Will of God. 
"Cleverness" is also false teachings, beliefs, false religious dogmas, fabrications.                                                                                                                               
"Cleverness" is one of the types of faith, false belief, false accusation of another person or group of people, any deed, phenomenon, event, maliciously committed, intentional for the sake of egoistic interests (religious, material, personal) or other low-level motives (envy, revenge, desire to get rid of the unwanted).
 Slander is usually observed in the situation of mutual hostility, competition and dosage-risks between people.

To slander directly and indirectly, explicitly or openly, many representatives of spirits of different religions used and use, showing themselves as slanderers,  taking advantage of spiritual ignorance of people, inflaming their low-men's inclinations, religious fanaticism, using them to fight with foreign believers, acting under the guise of fighting for the "number of faith". (For example - struggle against "heresies", expulsion of "dissenters" who disagree with the accepted traditional dogmatics, betraying "anathema" to people who do not agree with the purely literal interpretation of spiritual and figurative Biblical texts.
Slander in especially hidden and subtle forms in the modern world is often used by many leaders of the religious world. These types of slander are especially dangerous by their plausibility, which generates false faith, latent and explicit religious enmity.  
"Slanderers" are people who invent, spread a perverted, false interpretation of many sayings of the Prophets, Christ, Apostles, slandering the Will of God, His Righteous.