The Balaam teaching and the deeds of the Nicolaitans, or the abomination which was applyed to the church.

In the book of Revelation we read about two churches, the church in Ephesus and the church in Pergamum, and both of these churches were struck by the teaching and the deeds of the Nicolaitans, and God says that He hates this teaching.

Revelation 2:14 But I have a few things against thee, because thou hast there them that hold the doctrine of Balaam, who taught Balac to cast a stumblingblock before the children of Israel, to eat things sacrificed unto idols, and to commit fornication.
15 So hast thou also them that hold the doctrine of the Nicolaitans, which thing I hate.

In what way is this doctrine and this heresy expressed?

According to the context of the second chapter of the book of Revelation, the teaching of the Nicolaitans is directly connected with the teaching of Balaam and if we find out what the doctrine of Balaam is, we will understand what the doctrine and deeds of the Nicolaitans are.