What time of year is the baptism? I'm hoping it's at least two months from now, because you'll need that long for the soaps to cure. You might also be able to use the time of year as an inspiration for what sorts of design(s) to use.
Here's a very pretty mold with 16 cavities, holding almost 2 pounds of soap at a time. Fleur-de-lys pattern. Since it's for a baptism, the symbolism of the fleur-de-lys is appropriate: like the shamrock in Ireland, a three-petaled flower is sometimes used to demonstrate the idea of the Trinity within Christian traditions (or so I've heard).
Flowers are pretty:
Roses are often used in Christian tradition and decor, reminiscent of certain concepts and mentioned in the Hebrew Bible as well as the Christian Testament:
Perfect cubes:
Hearts:
Alternatively, you could buy a large slab mold with guest-soap-sized dividers, and do a colorful swirl of soaps instead of making it pretty by its shape. If you choose this route, I would go with this mold and this set of [url]dividers
http://www.brambleberry.com/Guest-Divid ... P4876.aspx[/url]