The Qadiyanis – who are also known as Ahmadiyyah or Ahmadis – are a misguided sect and false religion. There is a discussion in which their kufr and apostasy are proven in the answer to question no. 4060 

Based on that, it is not permissible for a Muslim to give his daughter in marriage to their followers or to marry any of them, as we have stated in the answer to question no. 45525. 

Based on that also, meat slaughtered by them is not permissible, because in Islam it is not permissible to eat meat slaughtered by any of the disbelievers except the People of the Book, namely the Jews and Christians, subject to two conditions: that the blood be drained out and that the name of Allah be said over animals that are permissible for us to eat, as we have explained in the answer to question no. 128632

Apart from meat that they slaughter themselves, it is permissible for the Muslim to eat their food, such as bread that they bake, sweets that they make, and fruits and vegetables that they grow, as we have explained in the answer to question no. 162654 

With regard to eating with them, it is permissible, especially for one who wants to soften their hearts towards Islam and encourage them to enter the faith and give up their beliefs; it is not permissible for one who eats with them because he likes them and loves them. 

The scholars of the Standing Committee were asked: 

What is the ruling on eating, drinking, sitting with and interacting with a disbeliever? Does it put one beyond the pale of Islam? 

They replied: 

Merely eating with a disbeliever, sitting with him and interacting with him when selling to him or buying from him, or other interactions in which there are worldly benefits that do not have any harmful repercussions for the Muslims in their religious or worldly affairs, does not put one beyond the pale of Islam. Rather treating the disbelievers with kindness and being nice to them is not regarded as sinful so long as they are not fighting us on account of religion or waging war against us. Allah, may He be exalted, says (interpretation of the meaning):

“Allah does not forbid you to deal justly and kindly with those who fought not against you on account of religion and did not drive you out of your homes. Verily, Allah loves those who deal with equity.

It is only as regards those who fought against you on account of religion, and have driven you out of your homes, and helped to drive you out, that Allah forbids you to befriend them. And whosoever will befriend them, then such are the Zalimoon (wrong-doers those who disobey Allah)”

[al-Mumtahanah 60:8-9]. 

The Prophet (blessings and peace of Allah be upon him) did business with the Jews, buying and selling; he traded benefits with them and made a deal with them after the battle of Khaybar, that they would cultivate their land in return for half of the yield. He ate from the foreleg of a sheep that a Jewish woman offered to him and his companions, in which she had put some poison to harm the Prophet (blessings and peace of Allah be upon him). 

With regard to sitting with them, eating with them and interacting with them on the basis of friendship, brotherhood, love and spiritual harmony, this is not permissible; rather it may amount to kufr (disbelief) that takes one beyond the pale of Islam in the case of one who approves of them and their religion, loves them, is sincere towards them or supports them against the Muslims, and the like – Allah forbid. Allah, may He be exalted, says (interpretation of the meaning): 

“O you who believe! Take not for Auliya (supporters and helpers) your fathers and your brothers if they prefer disbelief to Belief. And whoever of you does so, then he is one of the Zalimoon (wrong-doers, etc.).

Say: If your fathers, your sons, your brothers, your wives, your kindred, the wealth that you have gained, the commerce in which you fear a decline, and the dwellings in which you delight are dearer to you than Allah and His Messenger, and striving hard and fighting in His Cause, then wait until Allah brings about His Decision (torment). And Allah guides not the people who are Al-Fasiqoon (the rebellious, disobedient to Allah).”

[at-Tawbah 9:23-24] 

“You (O Muhammad SAW) will not find any people who believe in Allah and the Last Day, making friendship with those who oppose Allah and His Messenger (Muhammad SAW), even though they were their fathers, or their sons, or their brothers, or their kindred (people). For such He has written Faith in their hearts, and strengthened them with Rooh (proofs, light and true guidance) from Himself. And We will admit them to Gardens (Paradise) under which rivers flow, to dwell therein (forever). Allah is pleased with them, and they with Him. They are the Party of Allah. Verily, it is the Party of Allah that will be the successful”

[al-Mujaadilah 58:22] 

“O you who believe! Take not the Jews and the Christians as Auliya (friends, protectors, helpers, etc.), they are but Auliya to one another. And if any amongst you takes them as Auliya, then surely he is one of them. Verily, Allah guides not those people who are the Zalimoon (polytheists and wrongdoers and unjust)”

[al-Maa’idah 5:51]. 

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

End quote from Fataawa al-Lajnah ad-Daa’imah, vol 3, 1/431-433 

And Allah knows best.