Analysis of information sources in references of the Wikipedia article "부활절 달걀" in Korean language version.
During the spring cycle of festivals, ancient pre-Christian peoples used decorated eggs to welcome the sun and to help ensure the fertility of the fields, river ...
The early Christians of Mesopotamia had the custom of dyeing and decorating eggs at Easter. They were stained red, in memory of the blood of Christ, shed at His crucifixion. The Church adopted the custom, and regarded the eggs as the emblem of the resurrection, as is evinced by the benediction of Pope Paul V., about 1610, which reads thus: "Bless, O Lord! we beseech thee, this thy creature of eggs, that it may become a wholesome sustenance to thy faithful servants, eating it in thankfulness to thee on account of the resurrection of the Lord." Thus the custom has come down from ages lost in antiquity.)
The Christians of this region in Mesopotamia were probably the first to connect the decorating of eggs with the feast of the resurrection of Christ, and by the Middle Ages this practice was so widespread that in some places Easter Day was called Egg Sunday. In parts of Europe, the eggs were dyed red and were then cracked together when people exchanged Easter greetings. Many congregations today continue to have Easter egg hunts for the children after services on Easter Day.