I repeat:
Christians who do not follow Christ's two commands: "That you love the Father with all your heart and love your neighbor as yourself" are either in sin or commiting sin, as there is no violence in these commands. We are also to "go into all the world" and preach the Good News.
You will not find in the New Testament that Christ demands that Christians kill any one.
Human beings sin; God does not. Christ has not told His followers to kill anybody. IF someone mistakenly believes that he/she should kill non-Christians, they sin. They disobey God. Read about Paul (formerly Saul, a "Pharisee of Pharisees") of Tarsus, a former murderer of Christians, who thought he in the right and was doing what God would want him to do--getting rid of "blasphemers." God stopped him dead in his tracks, so to speak. People will do almost anything to justify their wrong behavior and attribute it as right when they are clearly in the wrong. Paul learned this himself and, ironically, became one of the revered and respected Christians.
Muhammed, on the other hand, advocated violence and murder of "people of the book" (e.g., Christians and Jews), and that his followers would be REWARDED in the afterlife for this. Christ, the Lamb of God, the Son of God, God in human form, would have none of His followers do such a thing.