Ever looked at a sentence in Russian, like “Я говорю по-славянски” (Ya govoryu po-slavyanski), and then one in Polish, “Mówię po słowiańsku”, and wondered how two languages from the same family could look so radically different? One uses an alphabet full of familiar letters, while the other employs characters like ‘Я’, ‘Ж’, and ‘Б’. This isn’t an accident; it’s the result of a fascinating 1,200-year-old story involving saints, empires, religion, and politics.

Welcome to the great Slavic alphabet divide. Let’s unravel why some Slavic languages write with the Latin alphabet and others with Cyrillic.

Two Brothers and a Mission

Our story begins in the 9th century with two brilliant Byzantine Greek brothers from Thessaloniki: Constantine and Methodius. We know Constantine better by his later monastic name, Cyril. They were scholars, theologians, and linguists asked to undertake a crucial mission.

Prince Rastislav of Great Moravia (a territory covering parts of the modern-day Czech Republic and Slovakia) was in a tough spot. He was caught between the powerful Frankish Empire to his west and the Byzantine Empire to his southeast. The Frankish priests spreading Christianity used Latin, a language his people didn’t understand. To assert his independence and connect with his people, Rastislav asked the Byzantine Emperor for missionaries who could teach the Christian faith in the local Slavic tongue.

There was just one problem: the Slavic languages had no writing system. How do you translate the Bible and liturgy for a people who can’t write their own language? You invent an alphabet, of course.

The First Draft: Glagolitic

Before Cyrillic came another, stranger-looking script: Glagolitic. This was the alphabet St. Cyril actually invented. It was a masterpiece of linguistic design, with unique and complex characters created specifically to represent the rich sounds of the Old Church Slavonic language.

Just look at some of its letters: Ⰳ (G), Ⰴ (D), Ⰶ (Zh). It looked like nothing else, and that was the point. It was a unique script for a unique people, distinct from both the Latin of the Franks and the Greek of the Byzantines.

Cyril and Methodius’s mission was a huge success. For the first time, Slavs had a literary language, which fostered a powerful sense of cultural and religious identity.

A Tale of Two Churches: The Great Cultural Divide

This is where religion and politics enter the stage and split the Slavic world in two. Even before the official Great Schism of 1054, the rivalry between Rome (the West) and Constantinople (the East) was intense.

The Sphere of Rome (Latin Alphabet)

The Pope and the Frankish rulers saw the use of a Slavic liturgy and alphabet as a direct threat to their authority. They insisted on the “three-language heresy”—the belief that Christianity could only be celebrated in Hebrew, Greek, or Latin. Ultimately, the political and religious pressure from the West was too great. Slavic peoples who fell under the influence of the Roman Catholic Church were pushed to adopt the Latin liturgy and, with it, the Latin alphabet.

• West Slavic languages: This includes Polish, Czech, and Slovak.
• Some South Slavic languages: This includes Croatian and Slovene.

The Sphere of Constantinople (Cyrillic Alphabet)

Meanwhile, the Byzantine Empire championed the work of Cyril and Methodius. After the brothers’ deaths, their students were expelled from Great Moravia by the pro-Frankish clergy. They found refuge in the First Bulgarian Empire, which became the new center of Slavic literary culture.

It was here, at the Preslav Literary School in the late 9th century, that a new, simpler script was developed. It was based heavily on the Greek uncial script, but it borrowed and adapted letters from Glagolitic for those uniquely Slavic sounds (like Ш [sh], Ц [ts], and Ч [ch]). In honor of the man who started it all, this new script was named Cyrillic.

Cyrillic was easier to write and learn than the ornate Glagolitic, and it quickly spread across the Eastern Orthodox Slavic world.

• East Slavic languages: This includes Russian, Ukrainian, and Belarusian.
• Other South Slavic languages: This includes Bulgarian, Macedonian, and Serbian.

So, here’s the general rule: If the nation is historically Catholic, its language uses the Latin alphabet. If it’s historically Orthodox, it uses the Cyrillic alphabet.

Special Cases and Modern Adaptations

Of course, history is never perfectly neat. Some countries sit right on the fault line.

Serbia is the prime example. With deep connections to both Eastern and Western traditions, Serbian officially uses both the Cyrillic and Latin alphabets. You can see signs, books, and websites written in both. The word for the Cyrillic script is ћирилица, and for the Latin, it’s latinica. Bosnian and Montenegrin also have a similar dual-alphabet status.

But what about the Latin-writing Slavic languages? The standard Latin alphabet doesn’t have letters for sounds like “ch” or “sh.” To solve this, they cleverly employed diacritics (the little marks and squiggles on letters).

• Polish uses letters like ł, ć, ż, and nasal vowels ą and ę.
• Czech is famous for its háček (ˇ) in letters like č, š, and ž.
• Croatian uses digraphs like dž and letters with diacritics like č, ć, š, and ž.

In a way, Cyrillic was more efficient from the start, dedicating a unique character for each sound (ч, ш, ж), while the Latin-based languages had to innovate to make their adopted alphabet fit.

A Living History

So, the next time you see a word like the Polish “cześć” (hello) or the Serbian “здраво” (zdravo), you’re not just looking at a word. You’re seeing a map of history—a testament to two brothers’ mission, the power of competing empires, and a religious divide that shaped the culture of millions.

For language learners, understanding this history is more than just a fun fact. It provides a deep context that makes the process of learning an alphabet—whether it’s mastering the 33 letters of Russian Cyrillic or navigating the diacritics of Polish—a much more meaningful and connected experience.