No, it can’t survive without indoctrination. Which means yes, it’s necessary.

Now the longer answer: any human enterprise only lasts as long as other people are used to it. That’s why advertisers try to drum up interest in specific products, why charities try to drum up interest in specific good works, and why men try to get women dru - ah, I mean, drum up women’s interest in them (yes, I’m kidding on that last bit). People can be “religious” and “spiritual” without indoctrination. However, organized religion can’t survive without it.

Look at the poor Greek Pantheon. The Egyptian. Bunch o’ others. Setting aside the starry-eyed New Agey types trying to revive those religions, they’re dead, Jim. And I’d say it’s because folks stopped indoctrinating other folks, at least in part.

Sure, there’s other reasons for their decline. Absolutely. But if nobody recruits for the faith, the faith is going to wither. So will any other enterprise that doesn’t at least semi-actively go after new bodies, or make new bodies to replace old ones.

In my not-so-humble-opinion.