The anti-christs: they are against Christ. They went out from us, but they were not of us. [meaning] They associated with the believers but they were not real believers. False teachers are impostors....But ye have an unction [oil]. The Holy Spirit anoints believers and can "know" certain things that unbelievers cannot. Do the gnostic false teachers claim to "know". Here is truth,  they cannot know, which even the simplest believer "knows" because he has the Spirit...."Every believer has been anointed with the Holy Spirit, and therefore knows that Jesus is the Christ". Ignore the false teachers, and look forward to the second coming of Christ with joyous confidence  [1 John 2: 18-28]....False Christs>>>Imposters claiming to be the Missiah [Christ in Greek]. Jesus associated the appearance of messianic pretenders with the fall of Jerusalem [Matt. 24:23-26]....Jesus said to be careful when the world loves a prophet's words because a prophet who is false is apt to be popular [Luke6:26].