Ad Limina by Cy Kellet
The Bishop of Mars faces intergalactic espionage on his journey from the frontier of space to the ancient halls of the Vatican.
The Vines of Mars by A.R.K. Watson
While tracking down his sister’s murderer, a Martian farmer discovers a secret that may destroy his colony.
Pink Noise by Leonid Korogodski
A classic Martian adventure that plumbs the spiritual life of a future humanity.