The green, yellow and red is often found in churches in Ethiopia, reflecting the colours of the Ethiopian flag. The "colourfullness" also includes many other bright colours. Green is very popular on houses as is light blue. The "brightness" the colours probably can give some good feeling for people struggling some times for their daily survival. Ethiopia is right now suffering its second season where the short rains (belg) fails and food relief are distributed to hard affected areas.
Many of these doors, some dating back to the early days of Christianity in Tigray (330 AC) have seen quite a few layers of paint during the years from natural colours to more modern types of paints.