This letter was probably written in Ephesus in AD 95–110. It was written to show that Jesus really came "in the flesh", and not only as a spirit, as some false teachers were saying. John says they are "anti-Christ", meaning against Christ. This false teaching is known as docetism. It says that Jesus only seemed to be a human person with a real body. John's letter says that Christians can tell if teachers are true. True teachers will say that say that Jesus came in the flesh. True teachers are also known by their ethics, and by their love.