The Red Door
Much symbolism surrounds the color of red for church doors.

Since the Middle Ages red doors have always been associated with giving sanctuary. People fleeing trouble and danger who sought safe haven and respite were given shelter in churches having red doors. It is said that one who claimed sanctuary in this way would be able to present his/her case before the priest and ask that justice be served.
Red is the color of the blood of Christ, who is a Christian’s entry into salvation.
Red is also the color of the Holy Spirit, the one who brings spirit into all life.
The feminine, the one who births all life, is associated with the color red.
The chalice, also associated with the feminine, holds the red wine, the symbol of the blood of Christ.
Red is the color of the Passion. Red doors say that symbolically one enters the church, the Passion, through death and resurrection in baptism. At an Orthodox baptism, the godparents present the candidate with red shoes as a symbol of walking the way of the cross by participating in the passion through the Eucharist.
Some say the reason for the red doors on Episcopal churches was to indicate that the mortgage for the church was paid off.
The children of Israel marked the lintels of their doors with blood as a sign for the Angel of Death to pass over. Red on the church doors signified all who entered were among the saved.