“Beloved, let us love one another, for love is from God, and whoever loves has been born of God and knows God. Anyone who does not love does not know God, because God is love. In this the love of God was made manifest among us, that God sent his only Son into the world, so that we might live through him. In this is love, not that we have loved God but that he loved us and sent his Son to be the propitiation for our sins. Beloved, if God so loved us, we also ought to love one another. No one has ever seen God; if we love one another, God abides in us and his love is perfected in us. By this we know that we abide in him and he in us, because he has given us of his Spirit. And we have seen and testify that the Father has sent his Son to be the Savior of the world. Whoever confesses that Jesus is the Son of God, God abides in him, and he in God. So we have come to know and to believe the love that God has for us. God is love, and whoever abides in love abides in God, and God abides in him. By this is love perfected with us, so that we may have confidence for the day of judgment, because as he is so also are we in this world. There is no fear in love, but perfect love casts out fear. For fear has to do with punishment, and whoever fears has not been perfected in love. We love because he first loved us. If anyone says, “I love God,” and hates his brother, he is a liar; for he who does not love his brother whom he has seen cannot love God whom he has not seen. And this commandment we have from him: whoever loves God must also love his brother. Everyone who believes that Jesus is the Christ has been born of God, and everyone who loves the Father loves whoever has been born of him. By this we know that we love the children of God, when we love God and obey his commandments. For this is the love of God, that we keep his commandments. And his commandments are not burdensome. For everyone who has been born of God overcomes the world. And this is the victory that has overcome the world—our faith. Who is it that overcomes the world except the one who believes that Jesus is the Son of God?” (1 John 4:7–5:5, ESV)
Love is the evidence of grace. Our love for God and our love for one another is found in him and comes as the result of his work in us. God's love made manifest by Jesus, and it is his divine work in us that we might live. We did not love God; we were his enemies and the children of wrath. Jesus is the clear demonstration of God's love, and he is the one who secures a favorable standing before a holy God. God's love produces a love for others and serves to show that he abides in us. We have been given the Holy Spirit because we abide in him. Christ gives us confidence for the day of judgment because we are clothed in his righteousness and are no longer condemned. You cannot say that you love God and hate your brother. Love for our brothers is a command and is optional because of circumstances, personality, or behavior. When one repents of sin and trusts the finished work of Christ, they are born of God and love God and desire to obey him. Overcoming the world comes by being born of God by faith in Jesus Christ.
The idea that the believer should never have fear is a misreading of this text. The believer need not fear the day of judgment because they have been rescued from sin and saved from the penalty that accompanies sin, namely death. The Bible does not contradict itself, and there are many places where we are told to fear the Lord because it is wise and right. It is the fear of the Lord which is the beginning of knowledge (Proverbs 1:7). The fear of the Lord is the recognition that the King of Heaven is infinitely holy and pure, and although he is near, he is transcendent, and it is wise to approach him with the correct posture of the heart. John returns to the truth that although one is not saved by works, those works serve as the evidence of grace and confirm that the person is truly regenerate. It is a joyful thing for the believer to obey their king. The new desires brought about by being born again cannot leave the believer in a settled defiance and so although the believer may sin it will not be the ongoing pattern of behavior. The believer needs the gospel every day. Repent, believe and repeat is the pattern of life for the child of God.