Many people will ask why is Christian speculative fiction necessary. I have been told by many Christian friends (and one secular college professor) that aliens and faith do not mix. It takes people away from reality, i.e. the Gospel. I believe that this can be a valid argument against Christians writing science fiction and fantasy, but if we look at the broken promises of secular science fiction over the last hundred years, we will find that this genre needs the Gospel message more than ever.
Most science fiction from the nineteenth and twentieth centuries promised that science and the human spirit would free itself from the bonds of "religious superstition" and reach upward to a better world. Much of the nineteenth century writers were promising that humanity was destined for a great utopia in the twentieth century. And again, this would all happen thanks to science and human endeavor.
The twentieth century indeed opened up to a new world--one of more death and destruction than all of recorded history. Science gave us poison gas in the First World War, and long range aerial bombardment and atomic weapons in the Second. Most of the major powers in the world have the capability to wipe out all life on the planet in the same amount of time that it takes to get a pizza delivered to your home. Human endeavor became highly efficient in exterminating six million people in death camps.
The promised utopia never materialized because many secular writers ignored that we humans are deceitfully wicked creatures at heart. It was only the staying hand of Christ that has kept us from destroying ourselves in the last century.
In this new century of pessimism and cynicism, Christians need to show that while human nature-and Satan-have not changed, God has not changed either. He is the same loving and merciful God that He has always been (Hebrews 13:8).
I do not know if we will ever venture out to the stars and colonize alien worlds before Jesus comes back, but I do know that it is the mission of the Christian SF writer to show humanity that God will be there to lead us to the true utopia (Revelation 22).