It is enough to be certain that it will. There have been various approaches dealing with the idea of Christ's eschatological return, the Second Coming, the Parousia. So-called postmillennialists taught that the church would largely succeed in evangelizing the world and in establishing God's reign on earth in preparation for Christ's return and the initiation of the eternal dominion of God. More frequent in recent years has been a more pessimistic response. Its advocates believe the world to be under Satan's power.
Evil is rampant.
Only the return of Christ can right things. Until that time Christians must just pray and wait. Most seem to be premillenninalists, understanding Christ's return as inaugurating a thousand-year period before the final Judgment. Presbyterians have emphasized confident hope over against such extreme optimism or pessimism. Since there is only one God who has created the world and intends good for all creatures, there is no need for despair or fear.