My objection is based on identifying two distinct entities: individuals and the social body. The two are linked and interdependent but each has a degree of autonomy. When I say "atheism and anarchism (of the individuals) are social ills" - I mean "they are bad for the social body" - a bit like a viral infection. A cell infected with a virus might think she's doing perfectly fine but she harms the body as a whole.

People are chemical machines programmed to survive and reproduce so of course we are to a large extent opportunists, what would you expect ?

If you accept morals do have a social function then I say "first point: check!" Second point that I propose is: individual freedom and social harmony are balanced against one another: the more of the one, the less of the other. Morals are a tool to shift the balance toward social harmony. And necessarily (if you accept the second point) away from individual freedom. Thus "enslavement" you are lamenting.

Yet if you agree that society has something good going for it when compared with anarchy, then consented enslavement (even when done opportunistically and not out of in-depth reflection and conviction) is good, valuable, desirable.