Jesus says >
"'But when you hear of wars and rumors of wars, do not be troubled; for such things must happen, but the end is not yet.'" (Mark 13:7)
What does this mean, that wars "must" happen? And how do we apply this?
He calls such things "birth pangs", symptoms of the world in turmoil on account of sin and death. Wars and rumors of wars, natural disasters, various calamities--these aren't signs of the end. These are the things that happen in a fallen world suffering in turmoil, in labor pains.
In the same way that labor pains precede childbirth, these are signs of this fallen age; but not signs of the end.
The end will come, Jesus says, without warning. The comparison with the "days of Noah" in Matthew 24 refer to the fact that people were going about their lives as normal--going to work, getting married, having children--when suddenly the flood came; in the same way shall be the Lord's return in Judgment on the Last Day. People will be working the fields, working the mills, making bread, etc.
These things "must" happen, in the sense that these are the labor pains, the "birth pangs" of the present, fallen, and suffering of this age. Compare with what the Apostle St. Paul says in Romans 8 (see Romans 8:18-25).
-CryptoLutheran