If you're delivering the good news of the Gospel in anger, you're far from effective. Professor of religion Theodore Pulcini has some keen insights into this horrible ploy in his Touchstonearticle "Cultivating 'Christian Anger.'"
Using St. John Cassian's "Institutes," Pulcini explores the perniciousness of anger and the catastrophes it causes.
The mark of a Christian is never to demean anyone. We should engage people with grace and when appropriate, humor. Anger, shrillness, and caustic words are the works of the Enemy of the Gospel.