What is the ruling on buying fast food and cold drinks from non-Islamic restaurants in European countries, and is it permissible to eat them?

The basic principle regarding beverages and similar items is permissibility, unless a reason for their prohibition is known, such as intoxicants or impurities. The same applies to fast food, with the exception of slaughtered animals. The basic principle regarding slaughtered animals is prohibition until their permissibility is known, especially in countries where unlawful slaughter is prevalent or where the slaughter is performed by those who are not People of the Book. The questioner should choose from the menu of these restaurants what is furthest from doubt, or inquire before eating.