I would say something for his home/ apartment: susan's idea of a pillow or cushion with an appropriate symbol is a good one. Table linens is another idea (dresser scarf, table runner, placemat). Book covers with a symbol would also be nice (basically a rectangle with the sides folded in a bit). small prayer bracelets with beads (not a rosary, per se, but for saying prayers) is another idea, but not knit.
did I say one project at a time?