This isn't some miracle. If you have organised religion, you usually end up reading from the scripture in the language it's written in. There are translations of course, but what really gets languages spreading is when they're adopted as an official language of the religion.
Funnily enough, having a different religion has been as good a reason as any for invading new places throughout history. The invaders teach them about their religion, and in turn help make a language official, since oppressors rarely decide to let the natives speak their own language.
Judaism and Hebrew, Catholicism and Latin, and Islam and Arabic. Each of these religions has a strong affiliation with a particular language. The Torah being in Hebrew helped Jews spread Hebrew across the world. Yiddish (a Germanic language with Hebrew influences) was once primarily used by Jews in Germany, but has spread across the Atlantic to North America, where some of its words have made their way into standard usage in American English. It took a lot of chutzpah to pull that off!
|They don't fit so well into hotel drawers.|
Catholicism had Mass in Latin for many centuries. Rome's conquest of most of the known world helped spread the language, and it continued to live long after the collapse of the Roman Empire. Why? Every priest across the world was conducting Mass in Latin. It's considered a dead language now, but it's still spoken in the Vatican and the Pope has even taken measures to promote it.
Look at the spread of Arabic from the Middle East to Africa. An empire helped this on its way, but convincing people that this was the right way to live your life certainly helped Arabic, the language of the Qur'an, get a foothold in Muslim areas of the world. Now Arabic spreads across such a large area that from one end to another the language is not mutually intelligible. The one thing in common is the Arabic used in the Qur'an.
|The Latin alphabet is starting to look pretty boring now.|
Whether you love or hate religion, it can spread languages and bring groups of people together. Religions can help certain languages to survive or even thrive. They're fine by us as long as they're not spreading hatred and prejudice, but encouraging linguistic awesomeness instead.