1 John 2:17

"The world and its desires pass away, but the man who does the will of God lives forever." NIV translation

Now, John gives us two reasons why we should not love the ways of this world. First, is that the things/ways of this world are only temporary and they will be removed. They will not be a part of the new heaven and new earth mentioned in Revelation 21. The second reason is that you cannot love this world and love God (do the will of God) at the same time. He tells us that only those that love God will live forever and Jesus said the same thing in John 14:21.

1 John 2:18 & 19

"Dear children, this is the last hour; and as you have heard that the antichrist is coming, even now many antichrists have come. This is how we know it is the last hour. They went out from us, but they did not really belong to us. For if they had belonged to us, they would have remained with us; but their going showed that none of them belonged to us." NIV translation

John tells us here that many people have gone out in opposition to the gospel of Jesus Christ and these are antichrists. There is also a specific antichrist coming that will not only be against the gospel but will set himself up in place of the Messiah (Jesus Christ). John goes on to say that we know it is the last hour because the real believers in Jesus are being separated from the antichrists. 

This passage is also one of the best at showing us that you cannot lose your salvation as many believe. John tells us that those that have walked away from the faith never really had the faith in the first place. Their salvation was not lost it was fake and, in fact, they are antichrists.

1 John 2:20

"But you have an anointing from the Holy One, and all of you know the truth." NIV translation

When we accept Jesus Christ as our Lord and Savior, we are then set apart to serve Him. This is what is meant by the term anointing throughout the scriptures as we see it was for priests as well as other items used to serve God in the temple. We should note that all of these items were set apart meaning they were not used part of the time for other purposes. Another term that describes this is consecration and it simply means that a person or thing is exclusively for God's purposes. 

We are told, in this verse, that this is from the Holy Spirit and by this same Spirit we know all truth. Our only part in this is accepting what is given to us and it costs us nothing. There are many today who are trying to sell an "anointing" as if they can sell something that is the work of the Holy Spirit. If you send in a certain amount of money, they will send you something that has an "anointing" on it just for you. There is no basis for such an "anointing". As Christians, we have the power to anoint things which simply means to give them to God and set them apart for His use.