New Defender's Study Bible Notes
2:3 know. This is the first of at least thirty-seven occurrences of “know” (Greek ginosko or eido) in I John. One of the prominent themes in this epistle is the assurance we have in Christ. This first test of how we know our salvation is real is that we desire to keep His commandments just because they are His commandments, and we desire to please Him.
2:5 keepeth his word. This is the second test of life in I John (note I John 2:3). If we are truly in Christ, we will keep (that is, guard) His Word.