Is it permissible to eat the meat slaughtered by Christians if the knife used to slaughter it is also used to cut pork, or if it is roasted in the same place designated for roasting pork?

The Quran, Sunnah, and the consensus of the scholars indicate that the slaughtered animal of the People of the Book (Jews and Christians) is permissible. There is no harm in using a knife or a grill that has been used for cutting or grilling pork, provided they are purified from impurity before use. If you know that something has been affected by impurity and you do not know if it has been purified after being affected, then it is not permissible to use it.