So you agree that morality is not absolute and unchanging, but must be interpreted in the light of the societal customs of the time?
Morality is unchanging. We often misunderstand the underlying moral issue. In the example you gave of the death penalty for some actions that Christians believe that Jesus set aside. The issue were perhaps two fold. Adultery is a mortal sin in both the OT and the NT. So why the execution in the OT and not the NT. The other issue was preservation of society. In a small nomadic tribe, adultery among its members could ripe the tribe apart. If the tribe is ripped apart it could cause devastation like no one being willing to work together for the good of the whole.
By the time Jesus came society was very different… Adultery could not lead to the destruction of an entire tribe.
There is another issue that in the OT many of the laws have to do with breaking the pagan customs of the Jewish tribes. Many of worshipers of the pagan gods engaged in orgies, ritualistic rapes, etc as part of the worship. So making adultery and fornication punishable by death could have been to end these practices. By the time Jesus came along the Jews had finally become truly monotheistic people.
Many of the laws in exodus, Leviticus and Deuteronomy serve the two purposes… to protect the unity of the Hebrew tribes and hence ensure their strength and to put an end to age old pagan practices that were against monotheism.
For example the commandment to wear tassels on their robes was to distinguish them as one people… sort of like the gangs do today with their ‘uniforms’.
The commandment to not cut the hair at the temples and to not trim the beard on the sides goes back to the worshipers of Ra (it think he’s the God). The worshipers of Ra used to cut their hair short at the temples and trim their beads so that they were rectangular… look at ancient Egyptian pottery. They are filled with paintings of men with this ‘do’. So the point was to not honor Ra and to not look like the worshipers of Ra.
The one about not planting a field with mixed plantings. This was in reference to a pagan practice of planting a field with mixed plants that were believed to have power. When the plants were in bloom, then the pagans would hold a ritual in the field, gathering some of the plants and burning them, etc. But just standing in such a field was believed by them to give the pagan worshiper power.
I’ve read some writing that say that the reason eating pork was outlawed is that it was the favorite sacrificial animal in many pagan sects. Remember that in the old days people ate the meat after a sacrifice. So not eating pig was a strong statement that the Hebrew tribe totally rejected paganism.
It’s not that morality is relative or changes, it’s that often we misunderstand the moral issue at hand.
