The only thing we should be ruthless about is our passion to love God and the people He calls us to serve. Unfortunately, some see themselves as chosen by God to eradicate all evil (which often means imposing their beliefs and opinions upon others against their will). History is replete with examples of monarchs, dictators and leaders who have tried to force faith. It has always resulted in some form of persecution.
We have only to remember what happened in the Dark Ages when the Church tried to impose their definition of truth upon the people of Europe. You can read about the devastating results in J.A. Wylie’s History of Protestantism.
1 Excerpt from Newsweek, Moderates Storm the Religious Battlefield, p. 89, January 7, 2007