The apostle John teaches that true Christian love serves as the identifying mark of genuine believers. While the command to love our neighbor is ancient, it becomes new through Jesus' perfect example and the Holy Spirit's power within us. Those who claim to walk in God's light while harboring hate toward others actually walk in spiritual darkness, becoming blind to their own stumbling blocks. Authentic Christian love flows naturally from our relationship with God, much like a loving spouse obeys out of affection rather than duty. The key is allowing the Holy Spirit to pour God's unconditional love into our hearts, producing fruit that demonstrates our faith to the world.