Although the book of 1 John is well known for its use of the word "love," various words, such as "know," "perceive," and "behold," occur almost as often.
Several of these words refer to the work of Christ in salvation. "And ye know that he was manifested to take away our sins" (1 John 3:5). "We know that we have passed from death unto life" (1 John 3:14), and "hereby perceive we the love of God, because he laid down his life for us" (1 John 3:16). This knowledge brings great comfort and assurance: "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" (1 John 5:13).
This knowledge should bring us into a life of submission and service: "But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him" (1 John 2:5). Similarly, "he that keepeth his commandments dwelleth in him, and he in him. And hereby we know that he abideth in us, by the Spirit which he hath given us" (1 John 3:24; see also 1 John 4:13).
This gives us confidence in prayer: "And this is the confidence that we have in him, . . . if we ask any thing according to his will, he heareth us: And if we know that he hear us, . . . we know that we have the petitions that we desired of him" (1 John 5:14-15).
The culmination of a life marked by salvation, assurance, empowering, and victory will be that we will be with Him and be like Him. "Behold |same word as 'know'|, what manner of love the Father hath bestowed upon us, that we should be called the sons of God" (1 John 3:1). JDM http://www.icr.org/article/5985/