Whence arose all the horrid assassinations of whole nations of men, women, and infants, with which the Bible is filled; and the bloody persecutions, and tortures unto death and religious wars, that since that time have laid Europe in blood and ashes; whence arose they, but from this impious thing called revealed religion, and this monstrous belief that God has spoken to man? The lies of the Bible have been the cause of the one, and the lies of the Testament [of] the other.
Some Christians pretend that Christianity was not established by the sword; but of what period of time do they speak? It was impossible that twelve men could begin with the sword: they had not the power; but no sooner were the professors of Christianity sufficiently powerful to employ the sword than they did so, and the stake and faggot too; and Mahomet could not do it sooner. By the same spirit that Peter cut off the ear of the high priest’s servant (if the story be true) he would cut off his head, and the head of his master, had he been able. Besides this, Christianity grounds itself originally upon the [Hebrew] Bible, and the Bible was established altogether by the sword, and that in the worst use of it—not to terrify, but to extirpate. The Jews made no converts: they butchered all. The Bible is the sire of the [New] Testament, and both are called the word of God. The Christians read both books; the ministers preach from both books; and this thing called Christianity is made up of both. It is then false to say that Christianity was not established by the sword. source
Nothing explains it better than the above video.