Muslims should work together to remove oppression from the oppressed and champion the rights of the down-trodden, regardless of whether they are Muslims or non-Muslims.
There is nothing in Islam to prohibit a Muslim from cooperating with non-Muslims, provided that such cooperation is proper, governed by rules of the Shari`ah. He Almighty also says: “Allah forbiddeth you not those who warred not against you on account of religion and drove you not out from your homes, that ye should show them kindness and deal justly with them. Lo! Allah loveth the just dealers.‏ Allah forbiddeth you only those who warred against you on account of religion and have driven you out from your homes and helped to drive you out, that ye make friends of them. Whosoever maketh friends of them (All) such are wrong doers.” (Al-Mumtahanah: 8-9)
Sheikh Muhammad Nur Abdullah, president of ISNA and member of the Fiqh Council of North America, states the following: “There is nothing wrong for the Muslim to cooperate with non-Muslim relief organizations for helping the needy people, Muslims and non-Muslims, everywhere, if these organizations are working only for the purpose of relief and they don’t have a different agenda that infringes on the Islamic faith. This permissibility is based on the following evidence:
1. Allah Almighty says: “And cooperate with one another towards righteousness and piety and do not cooperate towards sinfulness and aggression” (Al-Ma’idah: 2). This verse is general in the ruling, and it does not specify cooperation with Muslims only.
2. Allah Almighty says in Surat Al-Mumtahinah: “Allah forbids you not, with regard to those who fight you not for (your) Faith nor drive you out of your homes, from dealing kindly and justly with them: for Allah loveth those who are just.” So, this verse is very clear in stating that Muslims are allowed to cooperate with non-Muslims towards achieving common good, as long as they are not in the state of war with Muslims.
3. The Hadith of the Prophet (peace and blessings be upon him) in which he recalled the hilf al-fudul in pre-Islamic Jahiliyyah in which all parties joined hands to support the oppressed and defend the weak. The Prophet stated, “If I were invited to a similar alliance or treaty in Islam, I would welcome the idea.”
Therefore, there is no harm in dealing or cooperating with those organizations as long as they are working only for the relief purpose, and they don’t have any other hidden agendas.
As for Muslims receiving aid, it depends on the organization and its agenda. If it is a missionary organization that aims at Christianizing Muslims, then it is not allowed to accept this aid. If not, then there is no harm in accepting their donations.”