Conditions of Eating Meat Slaughtered by Jews and Christians
Question

I know that it is essential to say the name of Allah when slaughtering animals that are to be eaten, and that it is not permissible to eat from that over which the name of Allah has not been mentioned, but sometimes a Muslim has to travel to a non-Muslim country and stay there for several years, for work or study. Should he refrain from eating meat completely for this length of time or in this case is he regarded as compelled by necessity to eat meat or is it sufficient to say the name of Allah at the time of eating?
Praise be to Allah.Saying Bismillah when slaughtering meat 
Saying the name of Allah is a condition of meat being permissible, and it is not excused by forgetting or not knowing, according to the most correct scholarly opinion. 
Conditions of eating meat slaughtered by Christians and Jews
Meat slaughtered by one of the people of the Book (a Jew or a Christian) is permissible subject to two conditions: 

That the meat is slaughtered as a Muslim does it, by cutting the throat and oesophagus and letting the blood flow. If the animal is killed by strangling or electric shock or drowning in water, its meat is not permissible. Similarly, if a Muslim does that, the meat is not permissible. 
No name other than that of Allah should be mentioned over it, such as the name of the Messiah etc, because Allah says (interpretation of the meaning): 

“Eat not (O believers) of that (meat) on which Allah’s Name has not been pronounced (at the time of the slaughtering of the animal).” [Al-An`am 6:121]
And He says concerning prohibited things (interpretation of the meaning): 
“He has forbidden you only the Maytah (dead animals), and blood, and the flesh of swine, and that which is slaughtered as a sacrifice for others than Allah (or has been slaughtered for idols, on which Allah’s Name has not been mentioned while slaughtering).” [Al-Baqarah 2:173]
Shaykh Ibn ‘Uthaymin (may Allah have mercy on him) said:  
“What is meant here is that over which a name other than that of Allah is mentioned at the time of slaughter, such as saying “in the name of the Messiah” or “in the name of Muhammad” or “in the name of Jibril” or “in the name of Al-Lat” and so on.” (Tafsir Surat Al-Baqarah) 
The prohibition also applies to that which is offered as a sacrifice to the Messiah or to Az-Zahrah, even if they did not mention a name other than that of Allah over it. It is also prohibited.
Shaykh Al-Islam Ibn Taymiyyah (may Allah have mercy on him) said:  
“As for that which is slaughtered by the people of the Book for their festivals and as an act of worship to draw closer to someone other than Allah, as the Muslims offer their sacrifices to draw closer to Allah thereby, such as what they slaughter for the Messiah and Az-Zahrah, there are two reports narrated from Ahmad concerning that, the most well known of which in his texts is that it is not permissible to eat it, even if the name of someone other than Allah has not been mentioned over it. The prohibition on doing that was narrated from `Aishah and `Abdullah ibn ‘Umar (may Allah be pleased with them).” (Iqtida’ Al-Sirat Al-Mustaqim, 1/251) 
Can Muslims eat meat if they don’t know whether the name of Allah was mentioned over it or not?
If a Muslim or a person from the people of the Book slaughters an animal for meat, and it is not known whether he mentioned the name of Allah over it or not, it is permissible to eat from it, and the one who eats it should say the name of Allah, because of the report that was narrated by Al-Bukhari (2057) from `Aishah (may Allah be pleased with her), that some people said: O Messenger of Allah, some people bring meat to us, and we do not know whether they mentioned the name of Allah over it or not. The Messenger of Allah (peace and blessings of Allah be upon him) said: “Mention the name of Allah over it and eat.” 
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said:
“It is not essential to ask about what was slaughtered by a Muslim or a person from the people of the Book, and how it was slaughtered, and whether the name of Allah was mentioned over it or not. Rather that should not be done, because that is being obstinate in religious matters. The Prophet (peace and blessings of Allah be upon him) ate meat slaughtered by the Jews and did not ask questions.
In Al-Bukhari and elsewhere it is narrated from `Aishah (may Allah be pleased with her) that some people said to the Prophet (peace and blessings of Allah be upon him): Some people bring meat to us, and we do not know whether they mentioned the name of Allah over it or not. The Messenger of Allah (peace and blessings of Allah be upon him) said: “Mention the name of Allah over it and eat.” She said: They were new in Islam, and the Prophet (peace and blessings of Allah be upon him) told them to eat without asking, even though those who brought the meat to them may not have been aware of the rulings of Islam because they were new in Islam.” (Risalah fi Ahkam Al-Udhiyah wal-Dhakah by Shaykh Ibn `Uthaymin (may Allah have mercy on him))
Can Muslims living in non-Muslim countries eat meat?
Based on the above, whoever travels to a non-Muslim country where most of those who slaughter meat are Christians or Jews, it is permissible for him to eat their meat, unless he knows that they stun the animals or mention over them the name of someone other than Allah, as stated above. 
But if the slaughterman is an idol-worshipper or communist, it is not permissible to eat meat slaughtered by him. 
If the meat is prohibited , it is not permissible to eat from it on the grounds of necessity, so long as a person can find food to keep him alive, such as fish, vegetables and so on. 
Shaykh `Abd Ar-Rahman Al-Barrak (may Allah preserve him) said: 
“The meat available in non-Muslim countries is of various types. As for fish, it is permissible in all cases, because its permissibility does not depend on the way in which it is slaughtered or on the name of Allah being mentioned over it.
With regard to other types of meat, if the companies or individuals who produce meat are from the People of the Book, Jews or Christians, and it is not known from them that they kill the animal by electric shock, strangling or striking it on the head, as is well known in the west, then this meat is permissible. Allah says (interpretation of the meaning): 
“Made lawful to you this day are At-Tayyibat [all kinds of lawful foods, which Allah has made lawful (meat of slaughtered eatable animals, milk products, fats, vegetables and fruits)]. The food (slaughtered cattle, eatable animals) of the people of the Book (Jews and Christians) is lawful to you and yours is lawful to them.” [Al-Ma’idah 5:5] 
However, if they kill the animal by one of the methods mentioned, then the meat is prohibited, because in that case it is meat that has been strangled or killed by a blow. If those who produce the meat are not Jews or Christians, then the meat that they offer is prohibited. Allah says (interpretation of the meaning): 
“Eat not (O believers) of that (meat) on which Allah’s Name has not been pronounced (at the time of the slaughtering of the animal), for sure it is Fisq (a sin and disobedience of Allah).” [Al-An`am 6:121]
The Muslim should strive to avoid that which is clearly prohibited and be cautious of doubtful matters so as to preserve his religious commitment and to keep his body safe from being nourished with haram things.”
And Allah knows best.