I try to tell a story that's good enough to win the right to integrate eternal themes into it. If it's poorly written or comes across as a sermon, then obviously you don't reach people, because they're aware that you're imposing something on a story that isn't innate to it.
Heaven: A Comprehensive Guide to Everything the Bible Says About Our Eternal Home (Clear Answers to 44 Real Questions About the Afterlife, Angels, Resurrection, ... and the Kingdom of God) (Alcorn, Randy)