The angry and defensive manner is replaced by a sincere warmth and geniality.
Suppose I have a sincere religious belief that if I stop at a stop sign, God kills a kitten.
I take pride in being honest, sincere, compassionate, funny, discreet and friendly.
He sounds ever so sincere when he beckons the now sizable crowd into the tent, saying, “Welcome to our home.”
The Taliban leadership too has shown no sincere desire to remain involved in negotiations initiated by the U.S. in Qatar.
About that time the Bishops in assembly asked, "Is Simeon sincere?"
The devotion to and concern for our institutions are deep and sincere.
It is still more surprising to realize how sincere and devoted is all this homage.
The exclamation was sincere: at this moment she thought as she spoke.
I have sincere esteem for all who have been affected by them, having passed with them eight years of great harmony and affection.
1530s, "pure, unmixed," from Middle French sincere (16c.), from Latin sincerus, of things, "whole, clean, pure, uninjured, unmixed," figuratively "sound, genuine, pure, true, candid, truthful," of uncertain origin. Ground sense seems to be "that which is not falsified." Meaning "free from pretense or falsehood" in English is from 1530s.
There has been a temptation to see the first element as Latin sine "without." But there is no etymological justification for the common story that the word means "without wax" (*sin cerae), which is dismissed out of hand by OED and others, and the stories invented to justify that folk etymology are even less plausible. Watkins has it as originally "of one growth" (i.e. "not hybrid, unmixed"), from PIE *sm-ke-ro-, from *sem- "one" (see same) + root of crescere "to grow" (see crescent).