Galatians

Galatians is a famous Epistle of Paul to the church in Galatia, in central Asia Minor (now modern Turkey). He deals particularly with the issue of whether the Christians there (and elsewhere) should live as if under Jewish Law (e.g. should be circumcised), as people had been preaching this message amongst them, or should live by faith. He clearly says the latter.

The Galatians were Celts who had migrated to Asia Minor from Europe, and originally belonged to three tribes, the Tectosages, Tolistoboii and Trocmi. Their Celtic language almost certainly was still spoken when Paul wrote to them in Greek, though city-dwellers would know and use Greek.