Chapter 5:18-21 summarizes I John as follows:
Whosoever is born of God sinneth not.
Whosoever is born of God doth not commit (practice) sin; for his seed remaineth in him: and he cannot (practice) sin, because he is born of God. I John 3:9
He that is begotten of God keepeth himself.
And every man that hath this hope in him purifieth himself, even as he is pure. I John 3:3
The wicked one toucheth him not.
I have written unto you, young men, because ye are strong, and the word of God abideth in you, and ye have overcome the wicked one. I John 2:14
We are of God.
Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world. I John 4:4
The whole world lieth in wickedness.
Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world. And the world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever. I John 2:15-17
The Son of God is come.
Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ (Messiah Jesus) is come in the flesh is of God: And every spirit that confesseth not that Jesus Christ (Messiah Jesus) is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world. I John4:2&3
He hath given us an understanding.
But ye have an unction from the Holy One, and ye know all things. I have not written unto you because ye know not the truth, but because ye know it, and that no lie is of the truth. I John 2:20&21
We may know him that is true.
If we receive the witness of men, the witness of God is greater: for this is the witness of God which he hath testified of his Son. He that believeth on the Son of God hath the witness in himself: he that believeth not God hath made him a liar; because he believeth not the record that God gave of his Son.
And this is the record, that God hath given to us eternal life, and this life is in his Son. He that hath the Son hath life; and he that hath not the Son of God hath not life.
These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God. I John 5:9-13
We are in him that is true.
But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him. I John 2:5
We are in his Son Jesus Christ.
Whosoever shall confess that Jesus is the Son of God, God dwelleth in him, and he in God. I John 4:15
This is the true God, and eternal life.
He that believeth on the Son of God hath the witness in himself: he that believeth not God hath made him a liar; because he believeth not the record that God gave of his Son.
And this is the record, that God hath given to us eternal life, and this life is in his Son. He that hath the Son hath life; and he that hath not the Son of God hath not life.
These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God. I John 5:10-13
Little children, keep yourselves from idols. Amen.
John contrasts the word ”idols” with ”the true God” of v. 20. He has reference here to the false teachers who withdrew from the brotherhood with which they had been formerly associated (2:19). Their false beliefs and practices are the idols from which the readers are commanded to protect themselves. The false teachers upheld the world’s philosophy as superior to God’s revelation as demonstrated in their perversion of basic Christian teaching (faith, love, and obedience).*
I John 5:18-21
*Notes on I John 5:21 from the MacArthur Study Bible NKJV – Copyright 1979, 1980, 1982 by Thomas Nelson Inc.
…let the word of Christ dwell (take up its life) in you richly…