Yeah, but by dint of being human, people cannot follow 100% of Christ's teachings 100% of the time. None of us share His perfection. You're a Catholic, you know about the doctrine of original sin, right? We can't all be heretics, just because we're not perfectly following the word of Christ. So where is the line drawn? Christians are constantly getting inappropriately pissed off at people, because they're human. Sometimes they act on that anger. That's not peaceful or Christ-like. Luckily, there is forgiveness.
No one is perfect. The place where the line is drawn is simply between those who work hard to be good honest people, and do what's right as often as they can, VS those who use their religion as a tool for sinister objectives, popularity, or even poetic emotional gathering.
As I said, heretics hiding behind religion does not necessarily define the religion, any more then having German soldiers dressed as American soldiers amongst them made them American soldiers.
The teachings of the Catholic church have been based on the teachings of Christ, and those who practice otherwise, are simply not Catholics.
It's like saying that a police force is bad by nature and design because of a few mistakes and bad cops.
The police force has it's guidelines that it follows, and that defines what they are, just as religion does.
All throughout the churches dark times, they have produced great people, and the teachings although came close a couple times, ultimately never were forgotten.
This is very hard to see past to be quite frank, for myself included. I myself had a very hard time with the Church, being scientifically minded, with peoples emotional prophiganda and various other silliness clouding my prospective of exactly what the church is.
Barbaric behavior by Catholic heretics is not the church, it is their own separate business, that they simply are doing in the name of the church.
Also note that Christianity acknowledges this. If you spend allot of time studying with Catholics, you will find that they are more aware then anyone of the barbaric things that have and continually to happen in the name of Catholicism, and are relentlessly persistent in countering it.
On the opposition, one of the things that served as evidence to lead me to conversion is the prophecies about the persecution of Christian in the "end times", which I myself am in the process of putting together a very detail and realistic story about.
I think part of it is the display of timing.
Take this for example:

At one point in the Apocalypse, during the time of "the beast", it describes a social campaign against Christian, covering the whole world, much like the Nazi Campaign against Jews, except in this case, giving Christians the option to betray their faith in exchange for social and economic acceptance, and even their very lives.
The bible additionally describes this time, and what is to happen before and after.
Perhaps you have read the story of the beasts. This is generally considered the most confusing part of the bible, particularly do to historical references. Some of the finer Catholic Apologetics believe that the 666 thing happened during the time of St. John. It is true that their was a man who's name added up to 666 who did many similar things, but they failed to note a couple things, the most definitive as follows:

The bible states: All Who dwelt upon the earth. This would mean 2 things, 1, all who choose to live by the laws of man, and dwell in material living and lust, generally, people who do not value afterlife, and 2, that the entire world has to be discovered and controlled by a central government or union of governments, which was never accomplished until after WW II.
Their were many other things that place this at the end times, such as happening AFTER the Jews returned to Israel ( post WW II ).
Now, they have discovered that their was a second code number, believed to be 888 which biblical collars think is the number of the lamb. The Number of the lamb seams to be unclear, but the best I've been able to find is that it's 333.
However, The bible doesn't address 1 beast, but 2 of them. It addresses one having been slain to death, and then a beast representing the great nations of the world rising and healing it.
This is the scary part, Hitler was believed to be the "anti-Christ" for his campaign, and fulfilling many of the behaviors mentioned in the bible.
Their is a Nazi code, representing loyalty to Hitler, which is 88, where H is the 8th letter in the alphabet: 88 = HH = Hile Hitler.
Since WW II, the UN has gradually begun using many of the behaviors used by Hitler and the Nazis. Below are just a few:

* One sided media
* School control
* Social Dependency on the government
* Gun control
* Abortion
* Targeting minorities and religious groups for social hatred
* Excessive Government Programs

Although we may have not seen the worst, these practices result in very terrible human behavior, hence, fulfilling the prophecy of the 2 beasts. It is said that during this time, their will be a campaign against Christians, produced by governments and social systems, and the behaviors by heretics is and always has been one of the prime tools for making this happen.