Task: Question Answering
Input (English): Passage: The Catacombs of Rome contain most of the surviving Christian art of the Early Christian period, mainly in the form of frescos and sculpted sarcophagi. They show a Christian iconography emerging, initially from Roman popular decorative art, but later borrowing from official imperial and pagan motifs.  Initially, Christians avoided iconic images of religious figures, and sarcophagi were decorated with ornaments, Christian symbols like the Chi Rho monogram and, later, narrative religious scenes. The Early Christians' habit, after the end of their persecution, of building churches (most famously St Peter's, Rome) over the burial places of martyrs who had originally been buried discreetly or in a mass grave perhaps led to the most distinctive feature of Christian funerary art, the church monument, or tomb inside a church. The beliefs of many cultures, including Judaism and Hinduism as well as classical paganism, consider the dead ritually impure and avoid mixing temples and cemeteries (though see above for Moche, and below for Islamic culture). 
Question: What show a Christian iconography emerging, initially from Roman popular decorative art, but later borrowing from official imperial and pagan motifs?
Output (English): Christian art of the Early Christian period.