Note on Christian Science Fiction
Good Christian science fiction should look like science fiction, but taking place in the moral universe and atmosphere of Western Civilization: see, for example, Cordwainer Smith, R.A. Lafferty, Gene Wolfe, Tim Powers, and perhaps Madeleine L’Engle.
In sum, everything that is not atheist (Arthur C Clarke), not liberal (Asimov), not libertarian (Ayn Rand), not libertine (Heinlein), not socialist (Gene Roddenberry) and not decadent (Lord Dunsany, HP Lovecraft) will most likely land within reach of Western Civilization.
Nothing need be openly nor obviously Christian, nothing preachy, nothing heavy handed.
Simply tell a good story, solidly made, that reflects the reality of the human condition, good and bad, better and worse, without any fickle or foolish daydreams about human nature not fitting human nature. Note that nonchristian stories routinely portray human nature in stiff and unrealistic ways.
People would go mad at the sight of stars, Mr. Asimov? Really? Eyewitnesses to the Crucifixion would immediately convince the world without any fuss that all religion was bunk, Mr. Clarke? Say you so? One should sleep with whores out of courtesy to one’s hosts when visiting whoreland, Mr. Heinlein? Really? Adultery is lawful for persons truly in love, Mrs. Rand? Honestly? Or, my personal favorite, if Captain Kirk is split into a good and evil pair, a la Jekyll and Hyde, the bad side is filled with passion and energy rather than filled with vice, and the good side is indecisive and weak rather than virtuous? Really, Mr. Roddenberry? Honestly, is that the way good and evil works, or have you simply been reading too much Freud, and it has warped your brain?
Even the moral views of non-Christian civilizations, such as a story told from a Taoist viewpoint, ends up being shallow, morally or emotionally backward. Contemplate the difference between youthful and elderly Ursula K Leguin, or George Lucas. Ponder for yourself please, what it means that STAR WARS, the most famous and most fun sci-fi franchise of all time, started out as good, clean, wholesome fun, but then, by the time we are done with prequels and cartoons, the Stormtroopers, named after Nazi soldier units, are being portrayed as admirable.