There are millions of liberals in this country who view the number 1 problem in the world as overpopulation of the human race. Many of them rationally believe that if a few billion people would die earth would be a better place. Of course as long as it was not them. In the absence of religion you can rationalize anything as being good.
On this very thread, we have a poster from an obscure sect of Christianity who rationalizes slavery as being good. Of course, other Christians have rationalized it as being evil. In fact, just 150 years ago, most of our major Protestant churches split over the issue. One must conclude that from religion you can rationalize anything as being good.