The Lamb Among the Stars is a three book Christian sci-fi series that takes place in the distant future.
For ten thousand years the human race has expanded and lived in peace. It started with a great revival that ushered in a golden age of Christianity, and the symbolic millennium has proven to be at least 10 times longer than a mere thousand years.
On the most distant human planet Farholme, though, subtle changes are taking place. Even though it is known from history how evil influences people, they are ill prepared for a spiritual shadow that has fallen over them.
Book 1, Shadow and Night tells this story.
In Book 2, The Dark Foundations the storm clouds gather as both physical and spiritual enemies prepare an attack on the isolated Farholme. Not only are there physical battles to be fought, there are spiritual conflicts as well. The unseen is revealed as battles rage.
The final book of the series is The Infinite Day. The battle of the ages is drawing near and there is failure from unexpected sources. Humanity hangs in the balance.
Edit to add: As Chris Walley pointed out to me, I neglected to include one important thing: my recommendation! I give this series two thumbs up.