Og Mandino

What's really neat about the Orthodox church is that it's like walking back in time 2,000 years to the time of the Apostles, when they created these services. You walk into that and it's really like... living it. They have maintained the truth ever since the beginning.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.