The CONCERN (2:14-15)
You have there some who hold the teaching of Balaam
Balaam was a Jewish prophet in Numbers 22-25 (prophecy whatever someone wanted for the right price) (2 Peter 2:15)
King of Moab hired him to curse Israelites but God prevented him so he tried to corrupt them by idolatry/immorality (some believed that it was fine to mix the idolatry and immorality of their culture with their faith for greed)
You also have some who hold the teaching of the Nicolaitans
Seem linked to Balaam’s false teaching (some believe it goes back to the deacon, Nicolas in Acts 6:5 who led people into idolatry)
The church at Ephesus hated this false teaching (Revelation 2:6) while the church at Pergamum tolerated this false teaching