Q: Is it correct to say that whatever is morally right or wrong today (from God's view and declaration) has always been and will remain the same?
A: We cannot say that whatever was morally wrong at one point of time was, therefore, morally wrong at another point of time. There are certain things, such as adultery, that are always morally wrong. But there are other things that may be morally wrong now, though they were not in the past. For example, today it is immoral for a man to marry his sister or half-sister, an act that became wrong with the enactment of the Law of Moses. This was not morally wrong prior to Moses, and, so, when Abraham married his half-sister Sarah, he did not commit a moral sin. Neither did Jacob when he married two sisters, though such an act was later forbidden by Moses.