Question: who started the tradition of coloring easter eggs?
Answer: early Christians of Mesopotamia

of Jesus, from which Jesus resurrected. In addition, one ancient tradition was the staining of Easter eggs with the colour red "in memory of the blood of Christ, shed as at that time of his crucifixion." This custom of the Easter egg can be traced to early Christians of Mesopotamia, and from there it spread into Russia and Siberia through the Orthodox Churches, and later into Europe through the Catholic and Protestant Churches.  This Christian use of eggs may have been influenced by practices in "pre-dynastic period in Egypt, as well as amid the early cultures of Mesopotamia and Crete".