Mod-80,
IIRC tosafot and the Rema point out that the non-Jews of today aren’t idol worshipers so the prohibitions stated in the gemara aren’t applicable. We can even do business with them on their holidays.
Regarding staying indoors, B”H Jews aren’t systematically murdered on Christian holidays any more. I don’t think any shul anywhere in the world has cancelled Shabat services this year based on the custom you mention.