I believe that the prohibitions are a part of God's morals, his law. Because of that I believe they have always been in existence. God can not change and his morals can not change.
13 for until the Law sin was in the world, but sin is not imputed when there is no law.
This, right here, what
@aineo quoted, needs to be emphasized so much for so many people on so many topics, it's not even funny. Well, it is, but not in a funny-ha-ha way. More of a funny-sad way.
This one scripture right here is why I have no problem with Sarah being Abraham's sister/niece/whatever, with Lot and his daughters or Adam and Eve's kids doing.... you know. You don't see any finger-waving from the Almighty, the Creator of this Plane of Existence, for these specific people's relationships. Because it wasn't against the law,
at the time. Things that are not evil but prohibited
can change because it doesn't go against His character. I can decide when my son can and cannot do things. If I allow my son to do something and then later decide he can't, for whatever reason, I have not changed my character. It is just no longer allowed. Why is this so hard?
God had about 20 generations, a couple thousand years at this point, where if He saw that His people apparently didn't get the memo that sis over there was a no-no, you don't think He would have said something sooner?
@ke4ke, I used to believe as you do that when the Bible says that He doesn't change, then that means that all the laws must have been in effect from the beginning to the end and still are now. Period. But, if you really think about it, it's not true. It can't be true and it's not what he said. He said that He doesn't change. There are many examples of his Laws that were only meant for a specific time period, specific people, civil laws, ritualistic laws and His Moral Law.
Let's bring it back to something simple again. Romans 5:13 above. "For until the Law" there was a time there was no Law. "sin was in the world" yes, there was sin in this world and it was before the Law. "But" meaning there is an exception. "sin is not imputed" sin is not assigned/attributed/owned by someone. How does this happen? "when there is no law". Put it all together:
There was a time when there was no Law although there was sin in the world, but sin is not assigned or attributed when there is no law. If the Law was always in existence, and available, and known, to the people, this scripture is completely irrelevant and meaningless.