At the end of this phase of existence will come what the prophets called, “The Day of the Lord.” This is the day God will use His omnipotence to snuff out evil once and for all. He has heard our questions about how long bad things must continue to happen before He does something (Rev 6:10) and He has responded that the day will eventually come.
On that day, all those made in the image of God (be they human or angelic) that have ever existed throughout history will be examined and judged to see if they are granted the right to live on in a remade earth where only good happens and bad things are a distant memory.
Those who are welcome to enter this new world will be those who have given their lives to Jesus. Why? Because sin will not be tolerated there, for sin is why bad things happen. And in order for sin to not make its way into that new world, we need to (1) be forgiven of our previous sins which Jesus will do if we follow him, and (2) receive the Holy Spirit that empowers us to live good lives free of sin. Right now we can experience that in some capacity, but when the Day of the Lord comes, we’ll be given a new kind of resurrected body (1 Cor 15) that will conform us to the image of Jesus (1 Jn 3:2) and free us of sin in its entirety.
Don’t be confused, we won’t live perfect lives because God took away our free will, but just the opposite. We will live perfect lives because in this phase of human history we used our free will to ask God to make us perfect. On the Day of the Lord, He will answer this desire in our hearts and get rid of the sin in us once and for all. He will slay the beast that constantly tries to seduce us and we will continue on with a resurrected free will that can no longer fall prey to sin.
Bad things will not always happen and God in His omnipotence guarantees it. All that is wrong with the earth will be done away with and only His Son and all who look like His Son will remain. This is the future of the Christian.
The day will come where fallen spiritual beings will no longer stay immortal, but die like men (Ps 82:7) and be thrown into a fire prepared for Satan and his angels (Mt 25:41). The day will come where all of the afterlife will be emptied out before God’s throne and each person that has ever lived will be judged by Jesus, some going on to eternal life, and some meeting the finality of death (Rev 20:14-15). The day will come where all that is bad will be done away with, and from that point on we will never ask again, “Why do bad things happen?” For one day the world will be set right and the community that will continue on into that world will be set right as well.