For the period of ca. 800 BC - 800 AD, about 65,000 texts on papyrus are currently published, about half of which date from the Roman period (here defined as 30 BC to 450 AD). Papyri are usually split into literary papyri (Greek authors, Bible fragments, ...) and documentary texts (tax receipts, letters, administrative documents, ...).

For the documentary papyri, which form the largest group, a quick and dirty search on type in papyrological databases gives ca. 17,000 tax receipts. These documents were written and kept as proof of having paid a certain tax (of which there were a lot!), as the taxman could definitely try and make you pay twice. Another 8,000 texts are letters with various types of content: a boy angry with his father for not having taken him on a trip, instructions on payment of officials, ... To this we can add various forms of contracts (loans, sales contracts, ...), which account for another 6,000.

Turning to literary texts, almost 16,000 literary texts (mainly on papyrus and parchment) have been published. Christian texts seem to make up a good deal of these, numbering over 3,000. This includes both canonical and apocryphical texts. This is followed by fragments of Homer, who accounts for no less than 1,800 texts, usually the Illiad or the Odyssee. Saying the Biblical texts make up an insanely large proportion of the existing corpus may be a bit of an overstatement, but they do make up a good chunk of the literary papyri.

In terms of language, the overwhelming majority of these texts was written in Greek. This is followed by Demotic (Egyptian written in a cursive script), Coptic (Egyptian written with a Greek-based alphabet), and Latin (relatively limited).

Papyri are an incredibly important source for understanding the ancient world. They lay bare the breadth of the human experience, from the lowliest peasant to the highest functionary. They also show how advanced these societies were, in terms of economics, law, social organisation, and so on. Important research on these fascinating texts is ongoing, and new papyri are published yearly.

A fun little anecdote (I've forgotten the source, though), since the OP mentioned Christianity: Grenfell and Hunt, two famed papyrologists, first published the Oxyrhynchus Papyri, an enormous corpus of papyri found at what must have been a garbage dump in ancient times. In the first volumes of the publications, they purposefully added a significant number of Christian texts, because they hoped this would increase interest for the sponsoring of further excavations.

SOURCES:

[Trismegistos] (http://www.trismegistos.org/) (the most important papyrological database for metadata on papyri)

[LDAB] (http://www.trismegistos.org/ldab/) (now a sub-database of TM, focused on literary texts)

[HGV] (http://aquila.zaw.uni-heidelberg.de/start) (a Heidelberg-based database, which allows the user to search on type)

If you'd like to read some papyri, I'd suggest browsing this [link] (http://papyri.info/search?TRANSL=en). It's a search of texts with English translations in the most important database with full-text papyri.