Commenting on the lack of evidence of any art with a Christian content until c. A.D. 200, Ernst Kitzinger noted that:
The writings
of Clement of Alexandria and Tertullian are the principal witness to this
change. Although both authors were hostile to images, we learn from Tertullian
about chalices with representations of the Good Shepherd being in use in his
time, while Clement lists symbolic subjects which he considers suitable for
representation on seal rings. What is perhaps most significant is the fact that
both writers put the case against images on a broader basis than earlier
apologists had done. This suggests that the case was becoming urgent within the
fold; . . . (Ernst Kitzinger, Byzantine Art in the Making: Main Lines of
Stylistic Development in Mediterranean Art 3rd – 7th Century [Cambridge,
Mass.: Harvard University Press, 1980], 132 n. 33)
Further Reading:
Answering Fundamentalist Protestants and Roman Catholic/Eastern Orthodox on Images/Icons