This is Horror Stories for October 1935, and John Newton Howett really went all-out on this one. The ISFDB entry for this issue is here. The version of the cover used here is that preserved at Galactic Central.
Pulp Parade #57: And you thought your cousin’s wedding was a nightmare
I’ve often wondered just what story that cover was supposed to illustrate…
Blindfolded, head in a noose and a gun poking into the priest’s back. These guys must wear belts and braces!
And if he’s blindfolded, why the book?
I agree that the book doesn’t make a lot of sense, except to provided the viewer with a visual reference to make it clear that this gentleman is a minister of religion performing a wedding ceremony. Perhaps holding it allows him to steady his nerves (an experienced minister could probably do the ceremony from memory, in any event).
Usually it is the reluctant groom with the gun to his back.