Why are church doors painted red?

the red door tradition originated during the Middle Ages in England when it was a sign of sanctuary. In those days, if one who was being pursued by the local populace, shire reeve (sheriff) or gentry could reach the church door he/she would be safe. Nobody would dare to do violence on hallowed ground and, in any case, the Church was not subject to civil law. The red door was fair warning to pursuers that they could proceed no further. One who claimed sanctuary in this way would then be able to present his/her case before the priest and ask that justice be served.

In the earlier days of the church it was understood that a soldier could not pursue an enemy that had entered through the red doors of a church. The red doors were a symbol of refuge and sanctuary for all people who entered. To all concerned the red on the doors signified the blood of Christ that had been shed so that all who came to him could be saved. Anyone who passed through those doors was safe as long as they stayed behind them. Over time, Christian people began to see the red doors of the church as symbolizing not only physical refuge and safety, but spiritual refuge as well. The blood of Jesus, and of the Church's martyrs, that the red doors of the church symbolized, would protect you from evil, both physical and spiritual. The red doors spoke to the world of holy ground that existed inside those doors, space that had been purged and made clean by God's Holy Spirit. Today people choose to paint their church doors red for many of the same reasons that churches did centuries ago.

Church door painted in red has nothing to do with the church...this is their free choice.

I dont know but my guess is because God told some peeps to put blood on their doors so the angel will not kill their first born. So maybe those old ones are red because of that?

to ward off evil spirits like wearing a red ribbon

to guide those people who are russian to church

So the ladies of the night know where to go.