Sometime evil is the source of greater good.
For example : During the second world war we had to kill in order to preserve the freedom.
Should have God intervene? How? Why this time and not the other times?
I believe that good people have the capacity to take an evil situation and make the best of it.
Someone who is raped might develop stronger inner fortitude than they would have otherwise.
Someone with a disabled child might take less things for granted than they would otherwise.
Someone who recovers from cancer might have more appreciation for life than they would have otherwise.
Sometimes an evil like Hitler makes people appreciate a less evil president or country.
But it's a theist fallacy to say that bad things happen as part of some grand plan to make us stronger people. Why?
Surely you know of rich, spoiled, pampered people who lie, steal and cheat and might benefit from growth of character but managed decades to a lifetime of a crazy, fun lifestyle and never experience significant growth.
Similarly you may know people who are by all accounts, good people, who repeatedly are struck by tragedy.
A god who loves everyone and knows everything would surely not keep inflicting damage on the 12 year old girl in Africa having her privates raped and mutilated by warlords, yet largely spare Justin Beiber or Frank Sinatra or Joe Namath.
People are blessed or "allowed suffering" in this world in exactly the same way Santa Claus gives more presents to rich kids and does less for poor kids.
Some people suffer more because there is no god and life is not designed to be fair.
The fact that people can choose to grow from, or make the best of, a bad situation, is to their credit. It is NOT to the credit of some invisible benevolent gardener who felt it was good to "prune" Suzie by letting her uncle molest her so she'd "build more character" as part of "god's master plan".
I'm sorry, there's just no way.