Antichrists and deceivers are an expected source of trouble for the church; that's the message of the Apostle John as he sends off his quick note to the church, the book we now refer to as '2 John'.
This little book makes clear that there are 'many antichrists' in the world, and that they are intent on deceiving and leading astray those in the church.
John gives two imperatives in this little note. The first one has instructs us on how to handle false teaching, the second on how to handle false teachers.
In this sermon, the first imperative is considered - 'Watch yourselves'. This passage is an important reminder to those professing faith in Christ not to go 'beyond' the teaching of Jesus and his apostles. There is a warning here that warns of disaster to those who abandon the faith, but that has great assurance and promise for those who persevere.