2:24,25
Again, John urges them to stick with what they first heard. The gospel needs to be presented clearly, and then expounded and explained. Only by sticking with the gospel will we remain in the Father and in the son, and Jesus had told them the importance of abiding in Him (John 15:4). Then we will receive the promised eternal life.
2:26,27
John now makes it clear that he is writing these things about "those who are trying to lead them astray”. His readers were anointed, and this anointing was received from Jesus. It is quite possible that the false teachers claimed to have a special anointing, and were in some way belittling the people John was writing to. John assures his readers that they did not need anyone to teach them. This does not mean that we don’t need teachers, but only teachers who believe the gospel. John assures them yet again, saying that the anointing they have received was real, not counterfeit (as it was in the case of the false teachers. They must remain in Christ.