It should be a must and not at all an oxymoron.
Morals were a time sanctioned method of getting along with the others which was based on religious precepts.
In time people understood the benefits of cooperation versus thuggery and thus the need for the religious backup disappeared. Ethics were born.
Nowadays some try to convince us that life is a zero sum game (it isn’t) and that ‘ethics are for the faint hearted’.
Not true. This conviction arises from falsely understanding the Darwin’s natural selection as the ‘survival of the fittest’!
Ernst Myer demonstrates clearly that this is absolutely wrong: ‘what is “the fittest” ?’ ‘You can be ‘fittest’ only by taking into account one or more parameters but those parameters might never describe completely a situation. Moreover ‘situations’ have a knack for changing so becoming the ‘fittest’ is a useless performance. In NNT’s terms is a (futile) attempt at robustness. Mayr says that in reality natural selection is about the demise of the unable to adapt. (Ernst Mayr, What Evolution Is).
Now is anybody naive enough to believe that one can adapt to new circumstances solely by oneself, without any outside help? And what help can one expect while finding oneself alone in a corner after a long enough spell of behaving unethically?

PS Thanks Vince Pomal for the very interesting question!