1 John 4

John seems to provide a simple theme of love and keeping the commandments in most of his teachings -

"Beloved, let us love one another: for love is of God; and every one that loveth is born of God, and knoweth God.
8 He that loveth not knoweth not God; for God is love." (New Testament | 1 John 4:7 - 8)

Therefore -

"If we love one another, God dwelleth in us, and his love is perfected in us.
13 Hereby know we that we dwell in him, and he in us, because he hath given us of his Spirit." (New Testament | 1 John 4:12 - 13)

For -

"If a man say, I love God, and hateth his brother, he is a liar: for he that loveth not his brother whom he hath seen, how can he love God whom he hath not seen?
21 And this commandment have we from him, That he who loveth God love his brother also." (New Testament | 1 John 4:20 - 21)

And -

"By this we know that we love the children of God, when we love God, and keep his commandments.
3 For this is the love of God, that we keep his commandments: and his commandments are not grievous." (New Testament | 1 John 5:2 - 3)

"And this is love, that we walk after his commandments. This is the commandment, That, as ye have heard from the beginning, ye should walk in it." (New Testament | 2 John 1:6)

It is through faith, love, and keeping the commandments that we overcome the world -

"For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith." (New Testament | 1 John 5:4)