Explanation: When Vladimir the Great was mulling conversion away from paganism, as being a pagan gained him few allies, but many enemies, he considered several different faiths. The most prominent were Judaism, Catholicism, Orthodoxy, and Islam. Judaism did not impress him; Catholicism (or more correctly, Western Christianity as represented by German envoys, as the split between Catholicism and Orthodoxy was not fully formed) he regarded as lacking grandeur. Islam and Christian Orthodoxy (or more correctly, Eastern Christianity as represented by Byzantine/Greek envoys) remained - but Islam forbade drinking, while Orthodoxy forbade having multiple wives. What is a warlord to choose!?
Eventually, he settled on drinking being the more important factor, and converted to Orthodoxy. Cheers!