I love going to rummage sales but many are in Protestant churches. Is it a sin to do so? What about shopping at a Salvation Army thrift store? Would I be supporting their religion by shopping there?
While I cannot recommend donating to Protestant churches, and while I cannot generally recommend donating to the Salvation Army since there are Catholic charities (e.g., the
St. Vincent de Paul Society) that do much the same work, there is nothing wrong with going to church rummage sales or Salvation Army stores. Purchasing products or services is different than making charitable contributions.