2. And He [that same Jesus Himself] is the propitiation (the atoning sacrifice) for our sins, and not for ours alone but also for [the sins of] the whole world.
3. And this is how we may discern [daily, by experience] that we are coming to know Him [to perceive, recognize, understand, and become better acquainted with Him]: if we keep (bear in mind, observe, practice) His teachings (precepts, commandments).
4. Whoever says, I know Him [I perceive, recognize, understand, and am acquainted with Him] but fails to keep and obey His commandments (teachings) is a liar, and the Truth [of the Gospel] is not in him.
5. But he who keeps (treasures) His Word [who bears in mind His precepts, who observes His message in its entirety], truly in him has the love of and for God been perfected (completed, reached maturity). By this we may perceive (know, recognize, and be sure) that we are in Him:
6. Whoever says he abides in Him ought [as a personal debt] to walk and conduct himself in the same way in which He walked and conducted Himself.
7. Beloved, I am writing you no new commandment, but an old commandment which you have had from the beginning; the old commandment is the message which you have heard [the doctrine of salvation through Christ].
8. Yet I am writing you a new commandment, which is true (is realized) in Him and in you, because the darkness (moral blindness) is clearing away and the true Light (the revelation of God in Christ) is already shining.
9. Whoever says he is in the Light and [yet] hates his brother [Christian, born-again child of God his Father] is in darkness even until now.