Workers in the abattoir are followers of a number of religions
Question

                We understand that the meat slaughtered by the people of the Book (i.e. Christians and Jews) is permissible to Muslims. This cannot be argued since it is found clearly in the Book of Allaah. Of course we realize also that there are a few differences of opinion amongst the scholars in certain circumstances. Today I wish to ask about a particular circumstance: 
We live in a city in Canada and as you may be aware, Canada is a country made up of immigrants from all parts of the world. 
Therefore, if you were to go to a slaughter house you would find people from many different backgrounds working there. You may find Muslims, Jews, Budhists, Christians, Sikhs, atheists, etc.. working there. Of them there are those who are responsible for killing the animals. Generally it is not known to the masses who it is that is killing the animals (i.e. it could be an individual of any faith, we have no guarantee who it is) and so can we say that since we live in such a country then it is not important to know that information and that we should just eat the meat found in the market place? 
I ask this keeping in mind that there are Muslims who do slaughter in the Islaamic way and sell that meat. In fact dear Shaykh, this is a fitnah for many people and the problem is that they ask the Mashaayikh in most cases without explaining the details I just mentioned. It would be most helpful if you could clarify for us this issue in some detail.
Praise be to Allah.The Muslim has to be careful with regard to 
          this matter, and try to ensure that his food, drink and clothing are 
          halaal. It is well known that meat slaughtered by idol-worshippers such 
          as atheists and Sikhs etc., who are not Jews or Christians, is not permitted 
          for us to eat. 
 One of us Muslims could do the actual 
          slaughtering, and then hand the carcass over to someone else to skin 
          it and cut it up. 
 Written by ‘Abd al-Lateef. 
 Conclusion: 
 If it is slaughtered by a Muslim or 
          one of the People of the Book (a Jew or Christian), that is fine. If 
          it is slaughtered by someone else, then we should not eat it. If it 
          is slaughtered in an abattoir where there are followers of various religions, 
          including Muslims, Christians, Buddhists, Hindus, Communists and apostates 
          from Islam, and it is not known who has slaughtered the meat that is 
          on offer, then it should not be eaten. And Allaah knows best.