The afterlife is very important to Christianity. Given its significance, it's not surprising that the Church has looked to visual symbols to represent important aspects of it. The peacock, a bird known for incredible beauty, is such a symbol.
The peacock was believed by the ancients to have flesh that does not decay after death, and thus it became a symbol of immortality.
Because Christians believe that those who are saved will live forever, the bird was thought to be a good depiction on that conviction.
This symbolism was adopted into Christianity, and the peacock appears in many early Christian mosaics and paintings.
Also worth noting is that because of the way a peacock struts and displays its feathers, the bird is sometimes a symbol of human vanity.
The peacock is used in church decorations in the Easter season.
- - "birds, symbolic." Peter and Linda Murray, Oxford Dictionary of Christian Art (2004).
- Patricia S. Klein, Worship Without Words: The Signs and Symbols of Our Faith (2000).
- Symbols in Christian Art and Architecture by Walter E. Gast. Top illustration of peacock by Mr. Gast.