Praise be to Allah.

One of the conditions of meat being halaal is that the one who slaughters it must be a Muslim or a kitaabi (i.e., a Jew or a Christian). Hence meat slaughtered by a mushrik, Zoroastrian or apostate is not permissible and is not halaal. 

The Shi‘ah have a number of beliefs and actions that put them beyond the pale of Islam, such as their belief that the Holy Qur’an has been distorted, and that their Imams have knowledge of the unseen, and are infallible and cannot be heedless or forget. 

They seek the help of the dead and call upon them instead of Allah; they prostrate towards their graves; and they revile the best of mankind after the Prophets and Messengers, namely the Companions of the Prophet (blessings and peace of Allah be upon him), and regard them as disbelievers. This has been discussed previously in the answers to questions no. 1148, 10272 and 21500. 

Whoever believes in any of these things, or does any of these acts that constitute kufr (disbelief) has gone beyond the pale of Islam, and meat slaughtered by him is not halaal. 

The scholars of the Standing Committee for Issuing Fatwas were asked about eating meat slaughtered by the Ja‘fari Shi‘ah, knowing that they call upon ‘Ali, al-Hasan, al-Husayn and all their leaders, at times of hardship and of ease. 

They replied: 

if the matter is as the questioner said, that the group that he is referring to are Ja‘faris who call upon ‘Ali, al-Hasan and al-Husayn, and their leaders, then they are mushrikeen and apostates from Islam – Allah forbid – and it is not permissible to eat meat slaughtered by them, because it is “dead meat” (meat that was not slaughtered properly), even if they mentioned the name of Allah over it. End quote. 

Fataawa al-Lajnah ad-Daa’imah (2/264) 

They were also asked: 

I am from a tribe that lives near the northern border and we mix with tribes from Iraq whose madhhab is idolatrous Shi‘ah; they worship domes (shrines) and call them al-Hasan, al-Husayn and ‘Ali, and when one of them gets up, he says “O ‘Ali, O Husayn.” Nevertheless, some people from our tribe have intermarried with them. I tried to admonish them but they did not listen. I have heard that meat slaughtered by them is not to be eaten, but these people eat meat slaughtered by them and they do not care. We ask you to please explain what we should do with regard to what we have mentioned. 

They replied: 

If the matter is as you have mentioned, that they call upon ‘Ali, al-Husayn, al-Hasan and others, then they are mushrikeen in the sense of major shirk that puts them beyond the pale of Islam. Hence it is not permissible to give Muslim women to them in marriage, and it is not permissible for us [Muslim men] to marry their women. It is not permissible for us to eat meat slaughtered by them. Allah, may He be exalted, says (interpretation of the meaning):

“And do not marry Al-Mushrikat (idolatresses, etc.) till they believe (worship Allah Alone). And indeed a slave woman who believes is better than a (free) Mushrikah (idolatress, etc.), even though she pleases you. And give not (your daughters) in marriage to Al-Mushrikoon till they believe (in Allah Alone) and verily, a believing slave is better than a (free) Mushrik (idolater, etc.), even though he pleases you. Those (Al-Mushrikoon) invite you to the Fire, but Allah invites (you) to Paradise and Forgiveness by His Leave, and makes His Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) clear to mankind that they may remember”

[al-Baqarah 2:221].

End quote. 

Shaykh ‘Abd al-‘Azeez ibn ‘Abdullah ibn Baaz, Shaykh ‘Abd ar-Razzaaq ‘Afifi, Shaykh ‘Abdullah ibn Ghadyaan, Shaykh ‘Abdullah ibn Qa ‘ood 

Fataawa al-Lajnah ad-Daa’imah (2/264) 

Shaykh ‘Abdullah ibn Jibreen (may Allah preserve him) was asked about eating meat slaughtered by the Raafidis. 

He replied: 

Meat slaughtered by a Raafidi is not halaal and may not be eaten. That is because the Raafidah are usually mushrikeen who always call upon ‘Ali ibn Abi Taalib at times of hardship and of ease, even in ‘Arafaat and during tawaaf and sa‘i. And they call upon (‘Ali’s) sons and their Imams as we have heard many times. This is major shirk and apostasy from Islam, for which they deserve to be executed. They also go to extremes in describing ‘Ali (may Allah be pleased with him) and ascribing to him attributes which are befitting only for Allah, as we have heard them say in ‘Arafaat. Because of that they are apostates, because they regard him as a lord and creator who controls the universe, has knowledge of the unseen, has the power to bring benefit and cause harm, and so on. They also cast aspersions upon the Holy Qur’an and claim that the Sahaabah distorted it and erased many things from it having to do with Ahl al-bayt (the Prophet’s family) and their enemies. Hence they do not follow the Qur’an and they do not regard it as proof. They also impugn the senior Sahaabah, such as the first three caliphs and the rest of the ten (who were promised Paradise), and the Mothers of the Believers, and the well-known Sahaabah such as Anas, Jaabir, Abu Hurayrah and others. They do not accept their hadeeths because they are disbelievers, or so they claim, and they do not accept the hadeeth of Saheeh al-Bukhaari and Saheeh Muslim, except those hadeeths that were narrated from Ahl al-Bayt. They hold fast to hadeeths that have been fabricated or in which there is no evidence for what they say. Yet despite that they act in a hypocritical manner, saying verbally that which is not in their hearts, and they conceal in their hearts that which they will not express to you. They say “The one who has no taqiyyah (dissimulation) has no religion.” So do not accept their claim to be brothers and to love sharee‘ah, etc. Hypocrisy is a major tenet of faith for them, may Allah protect the Muslims from their evil. End quote. 

And Allah knows best.