Q: A Christian man lives with me. He calls me "brother" and claims that we are brothers. We eat and drink together. Is this permissible or not?
A: A Kafir (nonMuslim) cannot be the brother of a Muslim. Allah (Glorified be He) says, The believers are nothing else than brothers (in Islâmic religion). The Prophet (peace be upon him) said, A Muslim is the brother of a fellowMuslim.
Kafirs, whether they are Jewish, Christians, idolworshippers, Magi, communists or others cannot be fellow brothers of the Muslims. It is impermissible to consider them friends. However, there is no harm in eating with them at sometimes, whether in a public feast or an invitation. As for taking them as fellows and eating with them on a regular basis, this is impermissible.
You (O Muhammad ﺻـﻠﻰ ﺍﷲ ﻋﻠﻴـﻪ ﻭﺳـﻠﻢ) will not find any people who believe in Allâh and the Last Day, making friendship with those who oppose Allâh and His Messenger (Muhammad ﺻﻠﻰ ﺍﷲ ﻋﻠﻴﻪ ﻭﺳﻠﻢ), even though they were their fathers or their sons or their brothers or their kindred (people).
A Muslim should sever ties with Mushriks (those who associate others with Allah in His Divinity or worship) and hate them for Allah, but should not hurt or attack them unjustly if they are not warriors. However, they should not consider them friends. They can just eat with them causally without sharing any feelings of support or kindness towards them.
A Muslim should treat nonwarrior Kafirs according to the Islamic manners, fulfilling the trust to them, and abstaining from cheating, treasury and lying. If a dispute occurs between them, they should argue with them in a mild way and treat them fairly, according to Allah's saying, And argue not with the people of the Scripture (Jews and Christians), unless it be in (a way) that is better (with good words and in good manner, inviting them to Islâmic Monotheism with His Verses), except with such of them as do wrong