Is it permissible for a Muslim who is suffering from difficult living conditions to live with his aunt, who is married to a Christian, in her home, knowing that he cannot afford to establish an independent household? And is it Islamically valid for him to consider himself an adopted son to his adoptive parents?

The prohibited adoption is one where a person is attributed to the adopter as if they were their own child, thus falling under the rulings of mahramiyyah (unmarriageable kinship) and inheritance. However, sponsorship and care without attributing lineage are permissible. It is not permissible for a Muslim woman to marry a non-Muslim, as Allah Almighty says: (And do not marry [your daughters] to idolaters until they believe) and (Then if you ascertain that they are believers, do not return them to the disbelievers; neither are these [believing women] lawful for them, nor are those [disbelieving men] lawful for them). The adopter's sister must annul her marriage to the Christian man, and living with her while her husband is present is not permissible because it is a reprehensible act. One should seek permissible work and earn from it, for "It is better for one of you to take his rope and gather firewood on his back than to come to a man and ask him [for something], whether he gives him or withholds from him."