If we ought to be willing to lay down our lives for others, we ought to be willing to make those comparatively smaller sacrifices which are necessary to relieve them in their distresses. Unless we are willing to do this, we can have no evidence that the love of God dwells in us. We can show love through our words, but John seems to be saying this is an inferior form of love. He doesn't say to love in word AND deed - he suggests we don't even express our love through words IF it means we are going to fail to love in deed, through our actions.
We can't accomplish this without being saved - true salvation bears fruits of love. In the world, love does exist - but without God it has its limits. It is the Spirit of Christ within us that allows us to die to self and then learn to love as He loved. So while love and loving actions are very much part of essential Christian living, Jesus made it clear that without Him leading the way the love and wonderful works are empty. The Spirit is constantly calling to all who believe on Jesus Christ to live as He lived, to love as He loved, to be Him to all we see and hear. When this occurs, we can be confident in our hearts that God is with us, and we are with Him.
While it's true we have false prophets run amok today, who are more false teachers than those claiming to actually be prophets, John's advice in these verses was to them who were surrounded with divisions and threats to the faith. What John was really warning them about was people who claimed to be speaking for God. The claim at hand was that Christ was not a man of flesh and blood. John was there to tell them otherwise. He says here that every spirit that admits Jesus Christ came in the flesh is of God. He doesn't say this confession makes them a Christian or a saved individual. This is a starting point for us as believers when talking with people - do they believe that Jesus came in the flesh?
Being God's children separates us as true believers from the world that does not know God. Believers can hardly expect the world to understand their special relationship with God as His children. We cannot fully understand what will be the full result of being the children of God in the hereafter. We do know when we die, Christ will be revealed as He really is, and His people will be immediately transformed into His image. As we look with expectation to coming face to face with the risen Lord where we will share His glory, let us be motivated to rely more upon the Spirit to conduct our lives with purity.
The Father so loved that He gave the Son and now we too are expected to give others our love, our will, our time, our resources, our abilities, our very lives. Brotherly love is essential to the Christian character, and those who do not possess it cannot be called Christians. One of the greatest examples of non-brotherly love is that of Cain toward his brother Abel. Cain murdered Abel because of envy, a trait that has no place in the heart of a Christian. John warns believers that they will be hated by the world for the same reason - envy.
The antichrists were claiming faith in God while denying and opposing the Son. To do, John says, is impossible. Because Jesus is God's Son and the Messiah, anyone who denies the Son doesn't have the Father either. And, anyone who confesses the Son also has the Father. Many cultists today call themselves Christians, but they deny the deity of Jesus Christ.
True believers, who had been begotten of God had received the Holy Spirit to help the discern truth and reject falsehood. They didn't need another teacher. Persevering in the relationship with Christ ensures that believers will remain faithful.
Our righteousness cannot come by obedience to the Law - this will only produce sin. And since sin is the transgression of the Law, we know that we have to die to the Law and live by faith unto Christ as a means to be seen as righteous by God. Those born again as God's children cannot sin because His seed is in us. Sometimes our old nature revives and for a moment exerts its power. But that is just the former man/woman and not our true identity. The battle with the flesh is won through Christ and our identity will continue on after this life to God. It is who we are - children of love.
John is warning the children of the faith that the end was at hand. Spoken by an apostle of the Lord with such directness that there could be no doubt. He absolutely believed it was the end of something, and since we are still here we know the end he was talking about was the utter and absolute end of Jerusalem - the Nation, the temple, the Law, the geneologies - the end of it all. John uses the term "antichrist" to describe those who oppose the doctrine of Christ. These antichrists who once professed Jesus, showed through their apostasy they never had known Him and were therefore never really part of the body. Since the little children of the faith had been anointed by the Holy Spirit, they knew the truth.