Jesus taught His followers that they should be prepared to experience one of two things: oppression or empathy. He explains this to the Pharisee Nicodemus, who came to Jesus under the cover of night to question Him. The reference here to the light is a reference to Jesus Himself:
And this is the verdict [judgement], that the light came into the world, but people preferred darkness to light, because their works were evil. For everyone who does wicked things hates the light and does not come toward the light, so that his works might not be exposed. But whoever lives the truth comes to the light, so that his works may be clearly seen as done in God (John 3:20-21).
Those that come toward the light are on a journey that leads to producing works that are “done in God”, meaning accomplished by His power. To believe in Jesus involves conforming ones life to His truth through the gift of grace; this is why Jesus told Nicodemus that one must be “born from above” [heaven] in order to “see the kingdom of God” (vs. 3).
There are two kinds of people in the world: those who prefer the darkness and hate the light, and those who pursue the light by the grace of God. We are either drawn toward the darkness (our own doing) or drawn toward the light (by God’s grace).
St. Paul taught that for the those whose lives remain faithful to Jesus’ teaching oppression is inevitable:
In fact, all who want to live religiously in Christ Jesus will be persecuted (2 Timothy 3:12).
The word translated here as “religiously” (eusebos) is usually rendered “godly” or “piously”, reflecting holy living. St. Paul taught that this is only made possible because of grace:
For the grace of God has appeared, saving all and training us to reject godless ways and worldly desires and to live temperately, justly, and godly [eusebos] in this age (Titus 2:11-12).
Our holy living will draw those who are empathetic to the light, as Jesus taught:
You are the light of the world. A city set on a mountain cannot be hidden. Nor do they light a lamp and then put it under a bushel basket; it is set on a lampstand, where it gives light to all in the house. Just so, your light must shine before others, that they may see your good deeds and glorify your heavenly Father (Matt 5:15-16).