Perhaps there should be two levels of membership. Membership in the outer group would only require people to accept the identity; and there would be a social pressure to do the rituals recommended by the inner group. Membership in the inner group would require hard work and proving one's rationality by successfully completing some tests.

As usual, the religion already has it. The outer group is called "believers" and the inner group is called "priests".

In a hypothetical world ruled by rationalists, the priests would do the rationality training and try to be as free of bias as possible, and the believers would be advised to sign up for cryonics.