In the Old Covenant, the unclean and unholy had the ability to spread and contaminate that which was holy. For instance, if a person with leprosy touched a person without it, the latter person became unclean, even if they did not contract leprosy. In other words, unholiness was contagious rather than holiness.
Jesus reversed this situation. Jesus touched lepers and cleansed them (Mk 1:41). Because of Jesus, holiness overpowered unholiness. Now holiness is contagious instead of unholiness. This reversal is why Jesus could say that the unholy weeds are now to coexist with the holy wheat (Mt 13:30). His plan is that the holiness of the wheat should overpower the unholiness of the weeds, bringing conversion and creating a culture of holiness and life.
Why then is our western culture living in B.C. instead of A.D.? Why does evil seemingly proliferate unchecked? Why are millions of babies annually killed in surgical and chemical abortions? Why is prayer banned in schools? Why does the media become increasingly anti-Christian instead of pro-holiness?
To answer these questions, start by looking in the mirror. Does your face radiate God's love? (Ex 34:29) Can you look yourself in the face without needing sunglasses? If not, "fix your eyes on Jesus" (Heb 3:1). Devour His word constantly and let it become your joy (Jer 15:16). Gaze on Jesus often in eucharistic adoration and transform your face (see 2 Cor 3:18). Receive His eucharistic body and blood more often, even daily. Then let your radiant face infect the world with holiness (Mt 5:16).