1st John 1:7 (NET) states;
But if we walk in the light as He Himself is in the light, we have fellowship with one another and the blood of Jesus his Son cleanses us from all sin.
1st John 2:9-10 (NET) states;
"The one who says he is in the light but still hates his fellow Christian is still in the darkness. The one who loves his fellow Christian resides in the light, and there is no cause for stumbling in him."
1st John 3:23-24 (NET) states;
"Now this is His commandment: that we believe in the name of His Son Jesus Christ and love one another, just as He gave us the commandment. And the person who keeps His commandments resides in God, and God in him. Now by this we know that God resides in us: by the Spirit He has given us."
1st John 4:7-10 (NET) states;
"Dear friends, let us love one another, because love is from God, and everyone who loves has been fathered by God and knows God. The person who does not love does not know God, because God is love. By this the love of God is revealed in us: that God has sent His one and only Son into the world so that we may 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 atoning sacrifice for our sins."
Love is definitely the underlining theme in 1st John. However what does John mean by love? Look at the scripture above and notice what is bold and underlined. Love is fellowship (1st John 1:7). True love is shown when we have fellowship with one another. You don't get this by shaking hands and walking away. You don't get this from a friendly wave to a neighbor. You get this when you spend time with one another, and truly touch one another in each other's lives. John tells us that God is love. We need to love another in fellowship. We need to walk in the light (1st John 2:9-10) and be with our fellow brothers and sisters in the light.
Matthew 22:36-39 (NET) states;
"Teacher, which commandment in the law is the greatest? Jesus said to him, "Love the Lord your God with all your heart, with all your soul, and with all your mind. This is the first and greatest commandment. The second is like it: "Love your neighbor as yourself."
We love and worship our Lord. We need to love and fellowship with one another. This is true love. Be there for one another, be in each others lives, serve God and the church, minister to others, and be in the Light that is Jesus Christ.