If I saw a man attacking a woman I would certainly try to intervene; to get him away from her, even risking my own safety. But if I would do this for a woman I don't know, and me being of such small power as I am, how is it that God, when He sees these things, simply allows them to go on? Am I more loving and compassionate than God? (I hardly think so.) Why doesn't God intervene like we think He ought to?
The truth is that God is continually intervening in the lives of people. Once, before I was a Christian, I was speeding in my car, hit a wall at an angle and the car rolled over. But my friend and I were unharmed. The car that was approaching us wasn't hit either. If they had been even a second or two earlier, they would have. Is all this “blind luck”? Because of course, horrific car accidents do happen too. Whilst I can look back at that event and praise God for His grace toward me, for sparing my life that I might go on and later be a saved man, also by His grace; there are those who die in similar accidents, like the former wife of a friend of mine.
For any given tragedy, or whatever kind of evil we see in the world, we don't know why God chooses not to intervene. We can be thankful when He does, though. In fact, at the end of every day we can thank God that He has allowed us to live yet another day. And if a man saves a woman from being attacked, this too is ultimately God's grace toward her. But the fact that there is evil in the world is not God's fault, it is ours. The Bible says:
See, this alone I found, that God made man upright, but they have sought out many schemes. (Ecclesiastes 7:29)
At the fall of man, God cursed the whole Earth with death and decay. Not only would man die, but animals as well; and there would be natural disasters like floods and earthquakes. Why did God do this? It's in order to turn us to God for salvation. It's to show God's love in His whole plan of salvation for which Jesus, who is the incarnation of God, sacrificed Himself. It's to show His power in that He does redeem us from the bondage of sin and gives us victory over it, and will restore all of Creation to its former glory. Romans says:
For the creation waits with eager longing for the revealing of the sons of God. For the creation was subjected to futility, not willingly, but because of him who subjected it, in hope that the creation itself will be set free from its bondage to decay and obtain the freedom of the glory of the children of God. For we know that the whole creation has been groaning together in the pains of childbirth until now. And not only the creation, but we ourselves, who have the firstfruits of the Spirit, groan inwardly as we wait eagerly for adoption as sons, the redemption of our bodies. (Romans 8:9-23)
There are parts of this passage which might be difficult to understand, but we might at least summarise it in saying that the existence of evil in this world is God's way of creating a longing in us for God's redemption. We put ourselves in this predicament, and God will restore all things back to the way they were before we messed it up. But in God's wisdom He has kept us in the mess we've made so that we would look to Him. To those who do look to Christ and are saved through faith, regeneration does begin right now in this lifetime. It isn't immediately completed; we still struggle with our old nature, but we are given a foretaste of what our full redemption will be like. So whilst something like death is tragic and (in Biblical terms) unnatural, God in His wisdom has a purpose for cursing mankind with it. It's so that we might consider our need for God. Psalm 90 summarises it this way...
The years of our life are seventy, or even by reason of strength eighty; yet their span is but toil and trouble; they are soon gone, and we fly away. Who considers the power of your anger, and your wrath according to the fear of you? So teach us to number our days that we may get a heart of wisdom. Return, O LORD! How long? Have pity on your servants! (Psalm 90:10-13)
Why does tragedy strike and God allow it? Jesus handles this very question in light of recent tragedies in His day...
There were some present at that very time who told him about the Galileans whose blood Pilate had mingled with their sacrifices. And he answered them, “Do you think that these Galileans were worse sinners than all the other Galileans, because they suffered in this way? No, I tell you; but unless you repent, you will all likewise perish. Or those eighteen on whom the tower in Siloam fell and killed them: do you think that they were worse offenders than all the others who lived in Jerusalem? No, I tell you; but unless you repent, you will all likewise perish.” (Luke 13:1-5)
“Unless you repent, you will all likewise perish.” That is to say; death is the result of sin – look at the tragedies of this world and realise that the state of the world is because of sin. Therefore repent – which really means both to turn from sin as well as to turn to Jesus... repent so that you might be saved from this corrupt and cursed world.