Is it permissible for a Muslim to participate in the burial of deceased Christians, especially if they were his neighbors?

A Muslim should not follow the funeral procession of a disbeliever or participate in their burial, even if the deceased was their neighbor. This is the view of the majority of scholars. However, some scholars have permitted attending the funeral of disbelieving relatives, citing the action of 'Umar ibn al-Khattab with Abu Wa'il when his Christian mother passed away. As for visiting a sick disbeliever, there is no harm in it if it serves the purpose of softening their heart towards Islam.