religion is not the solution.
Many religions support equal rights
many people are not religious and never will be
many people will never be one specific religion, like islam
Even the Menonites for instance, have started introducing womens rights, enforced by the laws, and their birth rate has gone down in some areas.
BUT
A non religious solution exists.

Just take away women's rights.

No voting, no property rights, that's it.
If society collapses from the population decline, their rights will be taken away anyways. This is a gentler solution for all.
Or invent mass scale cloning.