From Kuntsevych's zealous study of the Church Slavonic Byzantine Rite liturgical books he drew many proofs of Catholic doctrine and wrote several original works. Throughout his adult life, he was distinguished by his extraordinary zeal in performing the Church services and by extraordinary devotion during the Divine Liturgy. Not only in the church did he preach and hear confessions, but likewise in the fields, hospitals, prisons, and even on his personal journeys. This zeal, united with his kindness for the poor, led great numbers of Eastern Orthodox confession Ruthenians to a religious conversion to the Eastern Catholic confession and Catholic unity. Among his converts were many important personages such as deposed Patriarch Ignatius, of Moscow, and