Rev 2:9

9 “I know your oppression, and your poverty (but you are rich), and the blasphemy of those who say they are Jews, and they are not, but are a synagogue of Satan.

(but you are rich) – the riches of the kingdom of heaven surpass anything in this world.

the blasphemy of those who say they are Jews and are not, but are a synagogue of Satan – why did Jesus use such strong language? This kind of strong language was also used by Paul to the Galatians: “if anyone brings you another gospel let him be eternally condemned” (Gal 1:8-9). Paul admonished the Gentiles not to observe the Jewish religious days: “you observe days and months….” (Gal 4:10). This was “another gospel.” The Gospel that Christ died for was the worship of God in the Spirit (Gal 3:2). We should not worship God, as Paul said: “according to the basic principles of this world” (Gal 4:9; Col 2:8). Yet, the Gentiles continued on their path of observing the Jewish days, including the Passover, the Preparation and the Day of Pentecost. To these, they added more days, leaving the worship of God in the holy spirit for a different gospel.