Evil, like the weeds is a counterfeit of reality. Goodness will prevail. Thus, as Paul says, we have hope while we wait for adoption, the redemption of our bodies. Yet, while we wait, there is always hostile power in the world seeking to destroy the good seed. There exists a struggle between the risen Christ and the evil one over the allegiance of humans.
Evil does exist, despite the unpopularity of notions of good and evil today.
Contemporary culture has effectively done away with evil and sharply limits how much influence God can be expected to have on humans. People are regarded as being morally directed by neither God nor evil - but simply by themselves and others. All is relative. Matthew reminds us that we are not morally free agents who take direction simply from ourselves. We stand under the direction of God or we opt to align ourselves with evil.