10 Precisely for this reason they found it natural to take a clear position in all the conflicts which were disturbing the societies as they became organized. They took as their own the difficulties and problems inevitable for peoples who were defending their own identity against the military and cultural pressure of the new Romano-Germanic Empire, and who were attempting to resist forms of life which they felt to be foreign. It was also the beginning of wider divergencies, which were unfortunately destined to increase, between Eastern and Western Christianity, and the two holy missionaries found themselves personally involved in this. But they always succeeded in maintaining perfect orthodoxy and consistent attention both to the deposit of tradition and to the new elements in the lives of the peoples being evangelized. Situations of opposition often weighed upon them in all their uncertain and painful complexity. But this did not cause Constantine and Methodius to try to withdraw from the trial. Misunderstanding, overt bad faith and even, for Saint Methodius, imprisonment accepted for love of Christ, did not deflect either of them from their tenacious resolve to help and to serve the good of the Slav peoples and the unity of the universal Church. This was the price which they had to pay for the spreading of the Gospel, the missionary enterprise, the courageous search for new forms of living and effective ways of bringing the Good News to the Slav nations which were then forming. For the purposes of evangelization, the two holy Brothers-as their biographies indicate-undertook the difficult task of translating the texts of the Sacred Scriptures, which they knew in Greek, into the language of the Slav population which had settled along the borders of their own region and native city. Making use of their own Greek language and culture for this arduous and unusual enterprise, they set themselves to understanding and penetrating the language, customs and traditions of the Slav peoples, faithfully interpreting the aspirations and human values which were present and expressed therein.
Source: Slavorum Apostoli (Vatican.va)