The Bible promises us that in the end good will win out over evil, and evil will be defeated—finally and completely. It tells us that "in keeping with his (God's) promise we are looking forward to a new heaven and a new earth, the home of righteousness" (2 Peter 3:13).
But you are right: Evil is very strong, and we see it almost everywhere. You see, right now we live in a world of spiritual conflict—conflict not just between good and evil, but also between God and Satan. While the Bible doesn't answer all our questions about this, it does tell us that Satan is very strong, and he has broad powers over the present world. The Bible says, "For our struggle is ... against the powers of this dark world and against the spiritual forces of evil in the heavenly realms" (Ephesians 6:12).
But listen: By His death and resurrection Jesus Christ broke the power of Satan! In fact, the Bible says that this is why Jesus Christ came into the world: "The reason the Son of God appeared was to destroy the devil's work" (1 John 3:8). Someday Christ's victory will be complete and all evil will be destroyed.
On whose side are you? Have you put your faith and trust in Christ—or are you unsure of the future, and unsure of your salvation? By faith ask Christ to come into your life today. Then thank Him that someday you will go to be with Him in heaven, where evil will never touch us again.