Analysis of information sources in references of the Wikipedia article "Lễ Phục Sinh" in Vietnamese language version.
Just so, on that first Easter morning, Jesus came to life and walked out of the tomb, and left it, as it were, an empty shell. Just so, too, when the Christian dies, the body is left in the grave, an empty shell, but the soul takes wings and flies away to be with God. Thus you see that though an egg seems to be as dead as a stone, yet it really has life in it; and also it is like Christ's dead body, which was raised to life again. This is the reason we use eggs on Easter. (In olden times they used to color the eggs red, so as to show the kind of death by which Christ died,-a bloody death.)
Red eggs are given to Orthodox Christians after the Easter Liturgy. They crack their eggs against each other's. The cracking of the eggs symbolizes a wish to break away from the bonds of sin and misery and enter the new life issuing from Christ's resurrection.
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.)