You're kind of asking why God doesn't just send Satan's people to hell before they have a chance to live. He says that he allows the weeds to grow amongst the wheat so as to not disrupt the wheat from growing. In the afterlife the results of people's behavior to finally come back to them. Until then, people are granted mercy enough to repent in between the time they committed the offense and when they die.
Matthew 13:24-30
The Parable of the Weeds
24He put another parable before them, saying, “The kingdom of heaven may be compared to a man who sowed good seed in his field,
25but while his men were sleeping, his enemy came and sowed weeds
c among the wheat and went away.
26So when the plants came up and bore grain, then the weeds appeared also.
27And the servants
d of the master of the house came and said to him, ‘Master, did you not sow good seed in your field? How then does it have weeds?’
28He said to them, ‘An enemy has done this.’ So the servants said to him, ‘Then do you want us to go and gather them?’
29But he said, ‘No, lest in gathering the weeds you root up the wheat along with them.
30Let both grow together until the harvest, and at harvest time I will tell the reapers, Gather the weeds first and bind them in bundles to be burned, but gather the wheat into my barn.’”
Also, the Bible calls for his people many times over to suffer on behalf of Christ, and to celebrate when people persecute you in the name of Christ. Suffering can produce gold and silver in the spirit.
Revelation 3:18-19
18I counsel you to buy from me gold refined by fire, so that you may be rich, and white garments so that you may clothe yourself and the shame of your nakedness may not be seen, and salve to anoint your eyes, so that you may see.
19Those whom I love, I reprove and discipline, so be zealous and repent.