John 3:16 says, For God so loved the world that he gave his one and only Son that whoever beleives in him would not perish but have eternal life. The gospel expresses God's love. In John's writings the world is a place rebelling against God. He sends his Son to an undeserving people. The previous verse speaks of Jesus 'being lifted up', primarily referring to the cross. There Jesus has taken our guilt so that we might know God's forgiveness. The following verses say that if we believe we are not condemned but if we refuse to believe in Jesus we stand condemned already. Without Jesus we will perish. In Jesus we experience eternal life, knowing God now and anticipating enjoying being one of his people forever.