Can Muslims Eat Kosher?
Question

In Canada, there are a lot of foods on which there is a symbol having to do with the ways of making food in the Jewish religion, which I do not fully understand. This symbol says that the food is kosher.
Once it is understood that the food has been made in accordance with kosher laws, is it permissible for us to eat it? Because many foods, even bread, include ingredients like monoglyceride and diglyceride, and I do not know whether the source is vegetable or animal, so it is difficult for me to buy food.
Praise be to Allah.What foods are Jews not allowed to eat?
Allah has forbidden to the Jews many kinds of good foods, as a punishment for their disobedience. Allah, may He be exalted, says (interpretation of the meaning):
“For the wrongdoing of the Jews, We made unlawful for them certain good foods which had been lawful for them.” [an-Nisa 4:160]. 
As for our Shari‘ah, it is an easy-going, tolerant law, as Allah has permitted to us all good foods (at-tayyibat) and He has not forbidden to us anything but that which is bad (al-khabaith). Allah, may He be exalted, says (interpretation of the meaning):
“This day all good things have been made lawful to you.” [al-Maidah 5:5] 
And Allah says, describing the Prophet (blessings and peace of Allah be upon him):
“he allows them as lawful At-Taiyibat ((i.e. all good and lawful) as regards things, deeds, beliefs, persons, foods, etc.), and prohibits them as unlawful Al-Khabaith (i.e. all evil and unlawful as regards things, deeds, beliefs, persons, foods, etc.).” [al-A'raf 7:157]. 
After examining the food laws followed in the Jewish religion today, it seems that all the foods that they regard as permissible are permissible for us in our laws, and there is no exception to that, as far as we know, except alcohol only. 
Can Muslims Eat Kosher?
The word kosher, which is used by the Jews, means that this food is in accordance with the dietary laws followed in their religion. 
Based on that, there is nothing wrong with a Muslim eating this food unless he knows that they have put alcohol in it . 
We will quote here a reliable text from a study of the Jewish religion in a book called Mawsu‘ah al-Yahud wa’l-Yahudiyyah wa’l-Suhyuniyyah (5/315-318) by Dr. ‘Abd al-Wahhab al-Masiri, who spent a decade of his life compiling and researching it. In this text he gives a detailed explanation on the issue of food and dietary laws in Judaism. 
In this book he says: 
“The laws having to do with food are called in Hebrew kashrut, which is derived from the word kosher; what it means is appropriate or befitting. 
This word is used to refer to the set of laws that have to do with food, preparation methods and the lawful manner of slaughter in Judaism. 
These are laws the origin of which is the Torah, and food that follows the laws of kashrut is called kosher. What this word means is food that is permissible to eat according to the Jewish religion. 
These laws forbid the Jew to eat specific types of food and permit him to eat other kinds. In fact the prohibitions basically have to do with meat, but there are some other prohibitions, such as the fruit of a tree before four years have passed since its planting, or any plant that was planted with another type of plant, as mixing plants, like mixed marriages, is prohibited. This prohibition applies only to “the land of Israel” i.e., Palestine. 
It is also prohibited to drink any wine that has been made or touched by a Gentile (i.e., a non-Jew). 
In fact it is also prohibited to eat bread or any other food prepared by a Gentile even if it was prepared in accordance with the Jewish food laws. 
There is also a prohibition on eating leavened bread during the feast of Passover. 
With regard to meat, the rulings are as follows: 
(a) It is permissible for the Jew to eat clean animals and birds. 
These are animals that have four legs and cloven hooves, have no eye-teeth or fangs, eat plants and chew the cud. The birds (that Jews are permitted to eat) are domestic fowl that can be raised in houses and gardens, and some wild birds that eat plants and grains. 
All animals and birds apart from these are regarded as unclean. Hence it is forbidden to eat horses, mules and donkeys because they do not have cloven hooves; it is also forbidden to eat camels because they do not have cloven hooves. Pigs are forbidden because they have eye-teeth (known as tusks), even though they have cloven hooves. With regard to rabbits and rodents that eat plants, they have claws and not cloven hooves (so they are not kosher). 
Unclean birds include all those that have hooked beaks or talons; these are birds that eat carcasses and carrion, such as falcons, vultures, owls, kites and (some types of) parrots. 
(b) It is forbidden for the Jew to eat the flesh of animals if they have not been slaughtered by one who is qualified to slaughter, in the lawful manner, after reciting the blessing or prayer for slaughter. 
(c) It is also forbidden to eat certain parts of animals, such as the sciatic nerve. 
(d) It is also forbidden to eat meat from which the blood has not been drained by means of salting (washing away remaining blood and salt, after putting salt on the meat and leaving it for an hour). 
(e) It is permissible to eat fish that have fins and scales. As for other sea creatures such as shrimp, octopus and so on, they are forbidden. The same applies to shellfish. 
(f) It is permissible for the Jew to eat four types of locust, but it is forbidden for him to eat other insects and reptiles. 
(g) It is forbidden to eat meat and milk at the same time. Hence it is forbidden to cook meat in ghee (clarified butter) or butter; rather it must be cooked in vegetable oil. It is also forbidden to eat meat and cheese or butter and the like in one meal, and one must wait six hours between eating one and the other. 
It is even forbidden to put meat in a vessel in which milk or cheese was previously put, or to use the same knife to cut meat and cheese and the like. Hence restaurants that offer kosher food have to have two sets of vessels, one for cooking meat and another for milk. 
It is not forbidden for the Jew to eat any kinds of vegetables or fruits; however it is not permissible for him to eat from the first four harvests of a tree. There is also a specific prohibition on yeast during the festival of Passover. It is also forbidden for a Jew to drink wine that was prepared or even handled by a non-Jewish person. 
To a large extent these laws led to the Jews becoming somewhat isolated. Daily food affects the rhythm of a person’s life and controls his social relationships with others, because the person who eats food that is different from the food of others will find himself separated from them, whether he wants to or not; he cannot share their daily life with them. Even those Jews who have tried to overcome Jewish isolationism have found it difficult to give up Jewish food, because it is not easy for a person to change the food that he is used to. 
The necessity of having birds and animals slaughtered by a qualified slaughterman according to their laws made it impossible for the Jew to live outside of the Jewish community. 
Reform Jews have criticised the food laws, because they prevented the Jews from developing and assimilating; they are of the view that these laws do not have any religious or moral foundation, so they do not adhere to them. 
Jews in Western societies have been faced with difficulties in obtaining food that is lawful for them, in places where there are no kosher food shops to meet their needs. 
In Israel the Chief Rabbinate has tried hard to implement the food laws in public life, such as on airlines and in hotels and restaurants. 
The majority of Jews in the United States and Soviet Union (more than 80% of them), who form the vast majority of the world’s Jews, do not apply any of the food laws; rather many of them eat pork and no more than 4% of them follow all of the food laws. 
It is no different in Israel, where approximately 30,000 people work in raising and selling pigs. It seems that more than half of the Jewish inhabitants of Israel eat pork , including many prominent figures in society – ministers and generals and even members of the Knesset – even though they had agreed to propose a ban on the selling of pork. 
There are a number of companies in Israel that raise pigs, slaughter them and sell the meat; the most significant of them is Kibbutz Mazara. 
The religious parties at present are putting a great deal of pressure on the Israeli government to issue a law prohibiting the selling of pork. 
As for the secularists, they fear that this would lead to pork being sold on the black market, which would be detrimental to tourism and the economy, and would force Israelis to go into Arab Christian areas to buy pork, just as they go into Arab areas during Passover to buy regular bread. 
From time to time discussions flare up about food that is lawfully permissible, especially since some of the members of religious institutions use their authority to issue certificates of permissibility for personal gain. 
In 1987 CE, the Rabbinate announced that a certain type of tuna was not kosher, even though the Union of Orthodox Jewish Congregations of America (or Orthodox Union) had issued a statement saying that it was kosher. It was understood from this that the Rabbinate in Israel wanted to expand its influence and dominate the kosher certification process completely. 
The conflict between the Sephardim (Jews who came from Spain and Portugal) and Ashkenazim (Jews who came from Germany and France) is also reflected in the kosher certification process. Thus we find that the Ashkenazi Rabbinate rejects the certificates issued by the Sephardi Rabbinate, and vice versa.”
To sum up: there is nothing wrong with the Muslim eating Jewish foods on which is written the word “kosher”, unless it is known that they have added any alcohol to it. 
And Allah knows best.