Search ShareCG on "biblical." The clothing available there is made for Paul and Pauline, but at least of some of them are dynamic so can be fitted to other figures pretty easily.

Paul and Pauline are included free with Poser 11.

Sixus1's Nativity props, linked above, are for DAZ Studio. Getting them into Poser will be difficult, since DAZ has removed the DSON importer from their site. The baby in the set requires the Genesis 8 female from DAZ, and Sixus' baby character (sold separately).

As an alternative, there's Baby Luna. She comes with newborn morphs, and is included with Poser 11.

If you want farm animals...there's a really cheap lamb in the store here. It's old, though, and not very well done.  DAZ has a better one, as well as a donkey and other animals. (If you wait for the inevitable Black Friday sale, they'll be much cheaper.) The Hivewire horse is included with Poser 11.