The article analyzes two cases of borrowing Zoroastrian mythological motifs by Syriac-speaking Christians during the period of Late Antiquity. The first example, attested in the writings of Ephrem the Syrian (4th c.), concerns the case of reinterpretation of the traditional image of biblical Paradise as a cosmic mountain, encircling the whole world. Most probably, it developed under a direct influence of the Iranian cosmological traditions regarding the mountain Alburz.