I first found John Morressy through his Iron Angel series - a low-key but excellent fantasy series. Eventually I picked up some of his other books, including much of the light-hearted YA Kedrigern series, and this book.
There are novels about religion in which the story exists primarily to carry a message, and those in which religion happens to fit the story. The Mansions of Space is very much in the latter camp. It's largely told from the perspective of a 'Mechanist', minimally religious free-trader sceptical of the monks' beliefs. While religion and faith are integral to the story, the effect is one of non-credulous respect rather than evangelism.
The plot is structured as a two-threaded chase, and Morressy handles it well. Where he does less well is with the characters. While the key characters are credible and interesting, they're not particularly engaging. I wanted to find out what happened to them, but I didn't feel a strong emotional link. The ending was satisfying, but nor particularly moving.
The book is nominally in the author's Sternverein [aka Del Whitby] series, but I haven't read most of the others, and didn't feel I'd missed anything. It's essentially a standalone in a shared universe. The cover, happily, has little to do with the story itself; there are no bikini-clad women asking for salvation.
All in all, a competent SF adventure that will hold your interest without demanding much involvement.