Mostly all of the "morality" people live by are fashion. Sure you can craft some example of "pure evil" if you want to but they hardly have any relevance in people every day life. For all the popular "morally right" things to do or not to do we just craft a set of exceptions that are in fashion.

"You should tell the truth" yes, probably you should but should you always? what if you can prevent trouble if you lie? what if you can save someone form getting hurts by lying? what if you omit something etc. etc.

"You should not take a life" except if self-defense, defense of someone else, if the person poses an imminent danger to you or someone else, the person is military personnel form a different country, the person is unborn etc. etc.