Should I believe that meat is halal if it is sold in a store that is owned by a non-Shia Muslim store owner? What about from a Christian or Jewish store owner? Can the slaughterer be a Christian or Jew?
If a Muslim owns the store or restaurant then you may believe him. Note that the slaughterer does not have to be Shi’a Muslim, he can be Sunni however he must not have animosity towards the holy household of Prophet Muhammad (saw). The slaughterer can not be a Christian or Jew, however they can work and serve in the store.