2:20
In one sense we are just ordinary people, but in another we are special, for we have been adopted as sons of God. In some ways it is like Jesus, He was the Son of Man, fully human, but He was also the Son of God, and could do amazing things. John expresses it by saying we “have an anointing from the Holy One, and all of you know the truth. This is a defence against any group that tries to make us feel inferior.
2:21
John assures them that they already know the truth. Again it is a counter against false teachings that seek to make us doubt. Remember that in Eden the serpent said “did God really say....” we should have confidence in the gospel.
2:22
We have had lifestyle tests, now we come to the key doctrinal test, and doctrine matters. Some try to tell us that to be concerned about right doctrine is a mistake, such people are the ones who are truly mistaken. The first test is denying that Jesus is the Christ. Jesus is indeed the Christ, He is the centre and the focus of everything. If we deny Jesus then we are also denying the Father, for the Fathers sent Christ in order to fulfil His plans.
2:23
The matter is very simple, we cannot have the Father without the Son. They come as a package., you cannot have one without the other.