Hanging electrically illuminated crescents and stars on the outside of buildings during Ramadaan
Question

Here in Jordan a new tradition has appeared and become widespread, which is hanging electrically illuminated crescents and stars on the outside of buildings and balconies to celebrate the blessed month of Ramadaan, throughout the month. Is that permissible, seeing that it involves extravagance and imitation of the Christmas trees which Christians put up in December? Is the people’s ignorance a valid excuse?.
Praise be to Allah.Firstly: 
We do not think there is anything wrong with putting up decorations such as lanterns and the like to celebrate the beginning of the blessed month of Ramadaan, but we should pay attention to a number of things, such as the following: 
1.That should not be regarded as an act of worship, rather it comes under the heading of permissible customs.
2.We should not be extravagant and buy these decorations for high prices.
3.These decorations should not include any images of animate beings or include any musical devices.
4.The mosques should avoid using such decorations, because they will distract worshippers.
The scholars of the Standing Committee were asked: 
There is a custom in some mosques during the days of Eid and Fitr and on other religious occasions of adorning the mosque with different kinds of colours and lights and flowers. Does Islam allow such actions or not? What is the evidence for it being permissible or otherwise? 
They replied: 
The mosques are the houses of Allaah, and they are the best spots on earth. Allaah has given permission for them to be built and be respected by proclaiming the Oneness of Allaah (Tawheed) and remembering Him, and for prayer to be established in them, and for the people to be taught about their religion in them and to be guided to that which will bring them happiness in this world and in the Hereafter, by cleansing them of abominations, idols, deeds of shirk, innovations and myths, and of filth and dirt and impure things, and by protecting them against idle pursuits and foolishness and raising voices, even if that is by making announcements about things that have been found and asking about something that has been lost, and other things that would make them like public streets and marketplaces. And it is forbidden to bury people in mosques, or to build mosques over graves, or to hang up pictures in mosques or draw pictures on their walls, and other things that would promote shirk or distract those who are worshipping Allaah therein and contradict the purpose for which they were built. The Prophet (peace and blessings of Allaah be upon him) paid attention to these matters, as is well known from his life story and his actions, and he taught them to his ummah so that they would follow his teachings and respect the mosque and take care of the places that were built to establish the rituals of Islam. By doing that, they are following the example of the Messenger (peace and blessings of Allaah be upon him), and there is no report from him (peace and blessings of Allaah be upon him) which says that he venerated the mosque by illuminating it or putting flowers in it on Eids and special occasions. That was not known at the time of the Rightly-Guided Caliphs either or the time of the guided rulers during the early generations which the Prophet (peace and blessings of Allaah be upon him) testified are the best of generations, even though the people advanced and became very wealthy, and they developed a fine civilization and adopted all kinds of adornment and colours during the first three centuries. All goodness is in following the guidance of the Prophet (peace and blessings of Allaah be upon him) and that of the Rightly-Guided Caliphs who came after him, and those rulers who followed their way after them. 
By hanging lamps on them or putting electric lights around the outside or on the minarets, and hanging up flags and banners, and putting flowers on them on Eids and special occasions to decorate them and venerate them is an imitation of what the kuffaar do with their churches and places of worship, and the Prophet (peace and blessings of Allaah be upon him) has forbidden imitating them in their festivals and worship. End quote. 
Fataawa Islamiyyah (2/20, 21) 
If the lighting in the mosque is sufficient there is no legitimate reason for adding anything else that serves no purpose, and that money should be used for something else. 
Majmoo’ Fataawa Ibn Taymiyah (31/206). 
Secondly: 
It should be noted that taking the star and crescent as a symbol of the Muslims has no basis in sharee’ah, and it was not known at the time of the Prophet (peace and blessings of Allaah be upon him) or the time of the Rightly-Guided Caliphs, or even at the time of the Umayyads. Rather it was introduced after that. Whatever the case, flags and banners should be in accordance with sharee’ah, and as there is no evidence that this (the crescent and star symbol) is prescribed in Islam, it is better to avoid it. The crescent and star is not a symbol of the Muslims, even though some Muslims have adopted it. 
This has also been discussed in the answer to question no. 1528. 
And Allaah knows best.