We all can recite John 3:16: “For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life.” Within the bigger context, John is drawing attention to the fact that Jesus explicitly stated that unless one be born again he cannot see the kingdom of God. A person must be born of the water and Spirit and Jesus concludes that “whoever believes in him may have eternal life” (vs. 15).
While keeping things in perspective, John reminds us that “God did not send his Son into the world to condemn the world, but in order that the world might be saved through him” (vs. 17). His judgment is that light came into the world but people loved the darkness because their works are evil. Evil people hate the light and love the darkness because light exposes their deeds (vs. 20). This is why people hated Jesus and wanted him dead.
However, “whoever does what is true comes to the light, so that it may be clearly seen that his works have been carried out in God” (vs. 21). In other words, people who do what is true naturally gravitate toward the light so that the works that are carried out in God can be seen and point others to God. The works that Christians do should always point people to God. Paul was incredibly adamant that people follow him as he followed the example of Christ. Everything he and the disciples did and said was meant to point people to God, and it was always done in the light.