My concern isn’t with the local decisions - I agree, if your local sacrifice meets your moral expectations for yourself, and that involves abstaining from reproducing, then have at it.

The danger I see is that, with most movements, once a “critical mass” of support is reached, there tends to be a sentiment of “us vs them”.

Then it’s less about accepting other people’s different beliefs (having x children vs having y or 0 children), and more of shaming/“forcing”/coercing non-believers to your side.

We see this with cancel culture today, and various other movements in recent times.