If Christian, then buy or make a cupola and stick on top of roof near the front entryway--even add a cross weathervane on top--that'd be your steeple. (If a real-type cupola, you could stick a bell in there.)
Take up stained glass classes and make the windows.
Google for old church furniture (pews, etc.).
Google for images of small churches/chapels.
For a different twist, get a glass greenhouse with a gable roof--same general shape as photo above. Basically a small version of the Wayfarers Chapel in http://www.wayfarerschapel.org/
. The more expensive greenhouses have wood beams. Wouldn't work for all climates though.