Can Muslims Pray in a Church?
Question

I am a Junior doctor working in the UK. We Muslim doctors are usually at work during Juma prayer time. Hence often UK doctors at work offer Juma prayer in small rooms which are either Multifaith rooms(where people from all faiths can pray, often idols are kept in these rooms which are covered during Juma prayer) or in dedicated Muslim prayer rooms. In my hospital there is a dedicated muslim prayer room where we offer prayer regularly at least for day time prayers, but still as this room is small, we offer Juma on the side in the church to be able to accommodate the large no of doctors attending Juma prayer. My question is, is Juma Valid in such all the above different places mentioned above. One of my acquaintance commented that, Juma is only valid in a place where all five daily prayers are being offered in congregation.
Praise be to Allah.It is permissible to pray in a church if there are no images or statues in it. 
Al-Bukhari included a chapter in his Sahih which he entitled: Chapter on praying in a “chapel”. `Umar (may Allah be pleased with him) said: “We will not enter your churches because of the images in them. Ibn `Abbas would pray in a “chapel” except a “chapel” in which there were statues. Ibn Hajar (may Allah have mercy on him) said: Chapter on praying in “chapels”; a “chapel” is a place of worship for Christians. The author of Al-Muhkam said: The “chapel” is the cell of the monk, or, it was said, the church of the Christians and the latter is the reliable view. The ruling on “chapels” also applies to churches, synagogues, hermits’ cells, temples in which there are idols, fire temples and so on.”
If there are images or statues in it, the jurists differed concerning the ruling on praying there in that case. Some of them are of the view that it is prohibited, but the majority is of the view that it is disliked. The reason given by those who regard it as prohibited is the general meaning of the evidence which indicates that statues and keeping them are prohibited, because the presence of these images prevents the angels from entering that place. 
Al-Bukhari (3225) and Muslim (2106) narrated from Abu Talhah (may Allah be pleased with him) that the Prophet (blessings and peace of Allah be upon him) said: “The angels do not enter a house in which there is a dog or an image .” 
At-Tirmidhi (2806) and Abu Dawud (4158) narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Jibril came to me and said: `I was going to come to you yesterday and nothing prevented me from entering upon you in the house where you were except that at the door of the house there was a statue of a man, and in the house there was a curtain on which there were images, and in the house there was a dog. So give instructions that the head of the statue at the door should be cut off, so that it will look like a tree. And give instructions that the curtain should be cut up and made into two pillows that will be placed on the ground and stepped on. And issue instructions that the dog be put outside.’” So the Messenger of Allah (blessings and peace of Allah be upon him) did that. And the dog was a puppy belonging to Al-Hasan or Al-Husayn (may Allah be pleased with them) that was under a bed, and he gave instructions that it should be taken outside.
This Hadith was classed as authentic by Al-Albani in Sahih Al-Jami`, no. 68. 
Ibn Qudamah (may Allah have mercy on him) said: “There is nothing wrong with praying in a church that is clean. That was allowed by Al-Hasan, `Umar ibn `Abd Al-`Aziz, Ash-Sha`bi, Al-Awza`i, and Sa`id ibn `Abd Al-`Aziz (may Allah have mercy on them). It was also narrated from `Umar and Abu Musa. Ibn `Abbas (may Allah be pleased with him) and Malik (may Allah have mercy on him) regarded churches as disliked because of the images. But we know that the Prophet (blessings and peace of Allah be upon him) prayed at the Ka`bah when there were images in it. It is also included in the words of the Prophet (blessings and peace of Allah be upon him): “Wherever you are when the time for prayer comes, pray, for it [the earth] is a place of prayer.” (Al-Mughni, 1/407)
Among those who were of the view that it is prohibited to pray in a church if there are images in it was Shaykh Al-Islam Ibn Taymiyah (may Allah have mercy on him). (See: Al-Fatawa Al-Kubra, 2/59) 
The prohibition on praying in churches does not mean that such a prayer is invalid; rather the prayer is valid although it involves sin, because the reason why praying in churches is not allowed does not have to do with the prayer; rather it is because of the images in those places, as stated above. So the reason for the prohibition is different from the prayer and other matters pertaining to it. 
The Standing Committee and Shaykh Ibn `Uthaymin (may Allah have mercy on him) issued fatwas stating that it is disliked to pray in a place in which there are images, but the prayer is valid if that takes place. 
In Fatawa Al-Lajnah Ad-Da’imah (5/377) [vol. 2] it says: What is the ruling on praying in the house or room in which there are statues of animals or humans for decoration? 
Answer: 
“It is prohibited to keep images or statues and put them in houses, because the Prophet (blessings and peace of Allah be upon him) said to `Ali (may Allah be pleased with him): “Do not leave any image without erasing it or any built-up grave without levelling it.” And because he (blessings and peace of Allah be upon him) said: “The angels do not enter a house in which there is a dog or an image.” It is disliked to pray in a room in which there are pictures hanging or statues, especially if they are in front of the person when he faces the qiblah. But the prayer is valid. 
And Allah is the source of strength. May Allah send blessings and peace upon our Prophet Muhammad and his family and Companions. (Standing Committee for Academic Research and Issuing Fatwas. Bakr Abu Zayd, `Abd Al-`Azeez al As-Shaykh, Salih Al-Fawzan, `Abd-Allah ibn Ghadyan, `Abd Ar-Razzaq `Afeefi, `Abd Al-`Azeez ibn `Abd-Allah ibn Baz.”
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said: “… As for the prayer, it is valid, but it is disliked to pray in a place in which there are images except in the case of necessity; if nothing else is available, then there is nothing wrong with it.”
To sum up,

There is nothing wrong with praying inside the church if it is free of images and statues, whether that is Jumu`ah prayer or any other prayer.
It is disliked to pray in a church if there are images or statues in it. If the Muslims need to pray there because there is no other place available and they cover these statues with something that will conceal them, there is nothing wrong with it and it is not disliked.

And Allah knows best.