The child of God shares God's own nature

1 John 2:28-3:10
The reason the world does not know us is that it did not know him.
But we know that when Christ appears, we shall be like him, for we shall see him as he is. All who have this hope in him purify themselves, just as he is pure.
Sin is lawlessness. And in him is no sin. No one who lives in him keeps on sinning.
The reason the Son of God appeared was to destroy the devil’s work.
How we know who the children of God: Anyone who does not do what is right is not God’s child, nor is anyone who does not love their brother and sister.
The child of God shares God's own nature. It is against that nature - out of character - to live a life of sin, to go on breaking God's law deliberately(故意) and habitually (the tenses of the verbs in the Greek make a distinction between this and the particular 'one-off' sins referred to in 1:10).
The difference between 'God's children and the devil's children' is that 'the devil's children' do not do what is right, or love others.
Why?
The reason people do not know us is they did not know Him. Son of God appeared is to destroy the devil's work, the devil is against God from beginning. 
No one can be son of God but do not do the right.
Sin id lawlessness, it is against the word of God. Those are who goes on breaking God's law deliberately and habitually.
We have the hope that when Christ appears, we shall be like him, so we have hope in him purity ourselves.
Identify who is children of God: anyone who does not do what is right is not God's child and does not love their brothers and sisters.
How?
Do what God likes us to do, righteousness, and love brothers and sisters as God loves us.