Moral law was created with the group in mind. It was never about the individual. The reason is the team can become more than the sum of its parts. Immorally which is a word for the opposite behavior, places the individual ahead of the team, making harder for the multiplier effect associated with the team. Leftist blame free market selfishness and greed for social problems; immoral, even though this is not against the law; harms no one according to the law.
Sex outside of marriage, can be fine in the context of the individual. If I have an affair with your wife and you never find out to be hurt, this is OK to the atheist. When this is extrapolated to the entire team doing it, you cannot protect all from the pain. It leads to higher social costs due to divorce, illegitimacy and the harming of the unborn via abortion. The team suffers. Immorality does not scale very well to the team. It might work on a smaller scale.
Moral law was based on 3D or integral thinking; team thinking, while immorality is more 2-D or differential thinking; for yourself. It is easier to reason for just yourself. It is harder to integrate everyone so all can rise. The dumb down to immorally was expected and has destroyed cultures; bad teams that lose their place in the league cultures.
The theist respect for authority, loyalty and sanctity is designed to build team cohesion. They are looking to get everyone on the same page, so the team can become more than the sum of its parts.
It would nice if we could run two experiments, side by side. One will use morality and the other immorally, with each team having to pay for any added expenses their orientation creates. Right now the moral have to carry the water for the immoral, via taxes, which clouds the results. In this experiment, no moral person would have to pay for any expense due to abortion, while all such expenses would need to come from the immoral side. Then we see which team rise higher.
If you look at the Corona Virus bill in the USA House, the Democrats are trying to bail out mismanaged Democrat run states, at the expense of the more efficient Conservation states, who work better as a team. This creates injustice, since immorality created the harm and need and should only be a Democrat team expense. As long as they can steal from moral teams, they never learn, but mismanage even more, due to immoral choices that only benefit their leaders.