God has created a world in which the potential for evil existed from the beginning. This is because God filled the world with creatures (both human and angelic) who had free will. This means that they had the power to choose to go against God. God is light and God is peace. In Him is no darkness and no evil. But in His providence He is allowing evil to flourish for a time in order to determine who will be chastened by it and brought to repentance, and who will be hardened by it and brought to destruction. Once every person has made their choice, whether to serve God or not, there will then be no more purpose for evil and it will be vanquished from the creation. Then, 'God will wipe away every tear from their eyes; there shall be no more death, nor sorrow, nor crying. There shall be no more pain, for the former things have passed away' (Revelation 21:4).