"And Nothing Else."
History can't be a complete reliving of the past, and most people looking at history have little time for anything but the briefest overview.
Those "highlights" will be the odd, unusual, difficult and different things which happened.  Such "history" will be representative of the problems and difficulties of a place and time, but will not represent the ordinary or mundane, or anything which occurs, like much good does, on a very small scale.
Thus we have a history of the bad things the Christian Church has done and been, without a representative sample of the good that Church has also always done.
If there had been less harm done over the centuries, it wouldn't overshadow the good quite so much for so many.
The medaeval church was community center, school, hospital, community garden and welfare office. The number of people helped by this system is incalculable, but comes close to being the entire population of a continent for a millenium.
I think I begin to see a correlation between internal Church corruption and periods of spastic Church policy, but I am not at all sure.  Church leadership had become quite corrupt by the tenth century, and I have to wonder if or how this ties in with the crusades.  After significant refreshment and renewal, cynicism and corruption again began to grow after the great plague, and reached absurd dimensions by the fifteenth century, certainly a spur for the inquisition as well as for the reformation and counter reformation.
History distorts by omission, and for every corrupt cleric there were a dozen good fathers.  For every life taken, unnumbered lives saved.  
It is right for the Church to question itself.  Other religions have not had the same failings.  
But my friends don't have to be perfect.  The Christian church, and religion in general, have done huge amounts of good, have been the locus of probably half the good ever done on earth.   Christian churches aren't making as many mistakes today, though they are also not providing charity as much as they once did,  it is perhaps more difficult in today's world.  They have plainly repudiated many mistakes of the past.  One of the bigger remaining mistakes the Churches are making, about homosexuality, bothers me, personally, and has hurt this poster, I imagine.
"Forgive us our Spasms, as we Adjust"