It depends on what deaths you attribute to Christianity. Are we talking about people who happened to be Christians, or people who killed *because* they were Christians? Are we talking about people who killed in a war, either as an act of defense or an act of aggression?
But, just for information, here are some numbers. Modern scholars estimate that some 250,000 people died in the Crusades. But that is the total for all ten Crusades, spanning a period of just over 300 years, and that includes the Christians who died as well as the Muslims who died. Interestingly, more people died in a single day of the bombing of Berlin in WWII than died in all ten Crusades, on both sides of the conflict, over a 300 year period.
Roughly 60,000 people were killed by the Inquisition. That is all four Inquisitions, covering all of Europe, and spanning a period of roughly 400 years. That, of course, includes people executed as foreign spies, witches, and serial killers (all of whom were evaluated by the Inquisition before being handed over for execution). Interestingly, that is actually fewer people per year than are executed by the state of Texas. It is actually really close to the number of people who are struck by lightning each year in England. It is also important to note that more men were executed for "witchcraft" than women, and that the witch-hunting did not pick up steam until the 16th century (many folks mistakenly believe it was during the Dark Ages or the Middle Ages).
The witch trials in the United States killed 19 people from the time that the colonies were first established until the death penalty for witchcraft was abolished. It is also interesting that it was the local Christian minister who finally managed put a stop to the Salem Witch Trials.