I do believe that humans need religion. Let's take moral values for example:

You could say that morality can be constructed solely from rational arguments or empathy a.k.a. the Golden Rule.

But I believe the problem for this is that arguments and empathy can be subjective.

Let's say self-beatings. This practice can be considered as an act of bravery, or self-redemption, according to some cultures. However, other cultures may view this practice simply as harming one's own body, inviting diseases to wounds, etc. Differing values.

Same as empathy, in which we would treat others as we would like to be treated. However, can a South African 20 year old know what a 70 year old Russian feels? Can a minister of a country empathize with the common man selling t-shirts at the night market?

Only religion provides the reason to break through all these subjectivities, by an objectivity, which is God, the creator of everything, which stands above everything.

Without religion, moral values would be as stable as fashion sense. Ever evolving, ever changing.

True, true. That is the reality of things. But if you consider an isolated environment, where a community only has to abide to one religion, everyone would conform to only one set of standards. Hence, you have stability. Arguments will be diffused by a higher principle, which is God.

Looking at the larger picture, there CAN be stability, not through total conformity but tolerance. I think major religions have already covered this aspect. By doctrines, at least. People's personal choices however, is an entirely different story.