By not locking themselves in their homes. Seriously, I don't understand the question. Religion isn't the only aspects of our lives. We have friends, family, work, hobbies, chores, etc. Lots of things that facilitate interaction with other people.
Well it's not like solitaries are actually solitary. They still have friends, families, jobs, hobbies, etc, they just practice their religion in private. That's a fairly small part of their life, compared to everything else combined.