There are a number of inscriptions in Arabic written in the Nabatean and other early scripts that predate Islam, largely carved in rock on tombs. Several of these are explicitly Christian. However, only five are in (early versions of) the actual Arabic script. It’s undoubtedly true that papyrus manuscripts also existed in this period - this is not what a rock-carvings-only script looks like, for one thing (too curvy) - but none have survived. The oldest surviving Arabic language, Arabic alphabet manuscript is a receipt from the Islamic era. Pre-Islamic Arabic poetry could have been written down - the technology existed - but we have no evidence that it was, and lots of evidence for a primarily oral culture.