Philadelphia (modern Alashehir, Turkey) twenty-eight miles southeast of Sardis was a commercial center located on elevated ground overlooking the fertile plain of the Hermus (Gediz) River. In 189 b.c. the king of Pergamum, Attalus Philadelphus, established Philadelphia and named the city to honor his brother.
Jesus knows their limited strength. He commends them because they have kept His word and have not denied His name.
We can’t have a relationship with the Lord if we reject His Word. Jesus is the Word. John 1:1-14 AWMI
He was obviously pleased with their good heart and pure motives.