I recommend you study the history of what happened in north and south america from 1500-1800. In 200 years 95% of all people who had been leaving in north america were dead. Now, was this all christian missionaries? Of course not... but it was done by christians for the most part; often in the name of the church (particulary in spain's case).
The thing is, people and their pomp have been distorting Jesus from the beginning. How anyone arrived at the conclusions that the Crusades or the Catholic Conquistadors were justified is beyond me. They did what they did and I'm certain that God is not silent on the issue. If we cannot truly repent then we cannot truly be granted amnesty under His grace. This is why Jesus stated that many will call Him by His name, but they will not be saved, because as He says,
"I never knew you." People fall into the religious pit all the time, and good Christians get lumped in with the bad yeast. Its religiosity that masquerades as righteousness, and unfortunately, many fall into it.
If ever I was going to give you good advice and to have you reject and forsake anything else that I say, take this one thing onboard. We don't judge Christ by Christians, judge Christians by Christ, as even the very name means 'Christ-like.'. Anytime a self-proclaimed Christian commits atrocities, such as what you described, never knew God. Jesus also warns that people will come in His name with the appearance of a sheep, but inwardly, they are ferocious wolves. There are only three types of people in this world: Sheeps, goats, and wolves, and by their fruits, you will recognize them.