How did Byzantine missionaries convert the Slavs to Christianity?

The Byzantines sent wave after wave of christian missionaries to the Slavic lands, which sorrounded the Byzantine Empire.

Two of the most important missionaries were Saint Cyril and Saint Methodious. They were brothers, and converted many slavs to Orthodox Christianity, specially those living in Moravia. They also invented the cyrilic alphabet to give a script to the Slavic languages, and help spread christianity faster. Hence the name of the alphabet.

They didn't want to take part in European or worldwide conflicts after seeing the bloodshed it caused, which is also why they stayed out of the League of Nations. Moreover they wanted economic growth from an internal view not funded by outside factors. It allowed as much growth as the US needed without being hindered. It thus lead to the cycle of prosperity and in the end the cycle of depression.