It might be prudent to avoid associating rationality with particular people or social institutions.
There’s always the risk that particular instances of rationality will result in disaster, or that Bad Guys will be painstakingly rational, and in the early stages, wouldn’t want to suffer the fate of religions, which often take reputation hits when their followers do nasty things.
Rationality could be advertised as a morally neutral instrumental value, i.e., Better Living Through Rationality.
On the other hand, we could sell rationality as a tool for atheists, drug policy activists, and stockbrokers, and publicly associate with their successes.
I would venture that emotivism can be a way of setting up short-run incentives for the achievement of sub-goals. If we think “Bayesian insights are good,” we can derive some psychological satisfaction from things which, in themselves, do not have direct personal consequences.
By attaching “goodness” to things too far outside our feedback loops, like “ending hunger,” we get things like counterproductive aid spending. By attaching “goodness” too strongly to subgoals close to individual feedback loops, like “publishing papers,” we get a flood of inconsequential academic articles at the expense of general knowledge.