If we claim to share a relationship with God and yet live in darkness [i.e., in a sinful way], we are lying and are not living a truthful life.

But the person who obeys what His teaching requires, truly in this person love for God has been made complete. This is [another way] to be sure that we are in [fellowship with] Him:

The person who claims he is continuing to live in [fellowship with] Jesus should also live the way He did.

Dear children, it is [now] the last hour [i.e., the final period of God's dealing with people on earth], and since you have heard that an antichrist [i.e., a person who is against Christ] is coming, even now [you should be aware that] many antichrists have [already] come. This is [one way] we know that this is the last hour.

not [hate each other] the way Cain did, who belonged to the evil one [i.e., Satan], when he murdered his brother [Abel]. And why did he murder him? It was because his [own] actions were evil and his brother's were righteous [See Heb. 11:4].

Little children [i.e., dear ones], we should not [merely] claim to love [people], or [even just] talk about it, but [we should love] by what we do [for them] in a genuine way.

And God lives in the heart of the person who [continually] obeys His commands, and he lives in [fellowship with] God. And here is [another] way we know that God lives in our hearts: It is by [means of] the Holy Spirit, whom God gave to us. [See Rom. 8:9, 11; James 4:5; I Cor. 6:19].

Here is the way God's love for us was demonstrated; He sent His one and only Son into the world so that we could have [spiritual] life through Him.

This is [one way] to know we live in [fellowship with] God and that He lives in our hearts: [It is] because He has given us His Holy Spirit [to live within us, See 3:24].

Here is what a complete love will do for us: It will give us boldness in [facing] the judgment day, because the way Jesus acts [regarding love] is the way we should act [while] in this world.

This is [one] way we know that we love God's [spiritually reborn] children: [It is] when we love God and obey what He commands us to do.

If anyone [of you] observes his brother [or sister] sinning [in a way that would not lead] to [spiritual] death, he should ask [God, in prayer, to help that person], and God will give him [spiritual] life, [that is], to such ones, provided their sin is not leading to [spiritual] death. There is such a sin that leads to [spiritual] death. [See Heb. 6:4-6; I Tim. 5:6; Heb. 10:26-27; II Pet. 2:20-22]. I am not suggesting that you should ask [God, in prayer] about such a situation.