Final answer:
St Vladimir was attracted to monotheism to unify Kievan Rus' and form strong alliances, specifically with Byzantium. Feedback on Judaism and Islam from emissaries was negative, leading to the adoption of Orthodox Christianity due to cultural compatibility and the allure of Byzantine practices.
Step-by-step explanation:
St Vladimir became interested in monotheistic religions as he sought a unifying faith for the diverse peoples of Kievan Rus' and to strengthen his rule, as well as to form stronger alliances with neighboring powers, notably the Byzantine Empire.
Through the process of examining different monotheistic faiths, emissaries provided feedback on the religious practices of these faiths.
The feedback on Judaism was primarily negative due to the loss of Jerusalem and the perception of the Jews as a weakened people without a homeland. As for Islam, the emissaries reported unfavorably on the Islamic prohibitions against alcohol, which was an integral part of Slavic culture.
Consequently, Orthodox Christianity was chosen, which not only aligned with the political and cultural interests of Vladimir but also offered the aesthetic beauty of Byzantine liturgy and art that impressed the prince and his emissaries.