Burying a kaafir in the Muslim graveyard

It
is not permissible to bury a kaafir in the Muslim graveyard, regardless of
whether he was adopted by a Muslim or not, or whether he had reached the
age of adolescence or not. But if there was any indication that he was
Muslim (or that he had become Muslim), then he may be buried in the Muslim
graveyard. It should also be noted that adoption [in the sense that the
child is given the name of the person who adopts him] is forbidden in
Islam, because Allaah says (interpretation of the meaning):

“Call
them (adopted sons) by (the names of) their fathers.” [al-Ahzaab 33:5]

 And
Allaah is the Source of strength. May Allaah bless our Prophet Muhammad
and his family and companions, and grant them peace.