Conservative

That's pretty much always what "no" means, right? Almost nothing people say is final, so in a different context and after having grown a bit, the topic can usually be revisited.

The important thing is to be open and trusting enough in a relationship that each partner knows when a "no" could change to "I'll give it a shot." That usually takes more than time, but some concessions from both parties.

It looks like JD Vance's wife is Hindu. I work with a few Hindus, and they're generally pretty open to discussions about religion. One celebrates Christmas with the nativity and everything, so sometimes we discuss similarities between Christianity (my faith) and their flavor of Hinduism, and occasionally we'll work in Islam (some of my other coworkers). If we can explore our religions like this in a workplace setting, with respect, surely a married couple with more trust can explore it as well.

There should never be any kind of force or ultimatum for something like this. I occasionally invite my coworkers to religious events, and they do as well. I've been to a Mosque for a service (and talked to the Imam after), and I've visited a Hindu temple a few times, generally avoiding special services so as to not distract (like Eid-al-Fitr or Diwali), unless explicitly invited (I joined a friend for the first night of Ramadan).

Conversion isn't something you can force someone to do, nor should you try, it's something they need to do on their own. You can invite them to learn, which is the first step.