1 John
King James Version (KJV)

“We know that we have passed from death unto life, because we love the brethren. He that loveth not his brother abideth in death.”
King James Version (KJV)
3:14 We know - As if he had said, We ourselves could not love our brethren, unless we were passed from spiritual death to life, that is, born of God. He that loveth not his brother abideth in death - That is, is not born of God. And he that is not born of God, cannot love his brother.
1Jo 3:14 We know that we have passed from death to life, because we love the brethren. If our hearts are filled with brotherly love this shows that we are God's children; and the opposite is also true.