The difference between performing an act based on religious faith and performing an act based on profit, helpfulness, revenge, kindness, ambition, security, scientific knowledge etc, is that faith-based actions have no fact-based rationale behind them.
Let's say one man kills another. If the victim is killed because he broke into a house and threatened the killer's family with a screwdriver, then the killer's actions were reasonable ones based on an assessment of the facts (the guy has a weapon and could kill my children with it), and a reasonable and predictable result(slugging the guy will render him incapable of killing my kids). If, on the other hand, the victim is killed because he is an infidel walking down the sidewalk who harbors the spirit of Satan, the killer's actions are unreasonable ones based on psychotic mythology(I am doing the will of a good invisible being who says this man's evil invisible being is out to hurt me), and an unproveable outcome based on this psychosis (I will detonate a bomb on my chest simultaneously sending the infidel to hell and me to paradise). The second example illustrates a simple fact : No one would commit such an act unless he were either totally delusional, or laboring under the effects of faith.
I will not argue that some strains of religious dogma are less virulent than others. You don't hear about a lot of Buddhist suicide-bombers. But most religions are based on a core mythology which requires a suspension of rational thought in order for the believer to buy in. Once this suspension of rationality is achieved, successive sacrifices of reason in the name of faith become easier to swallow. Follow this path and you will find a pandora's box of irrational activity.
When George Bush was contemplating what he should do about the problem of Sadam Hussein, he reported that he had discussed it with his "Father". And he didn't mean George Bush Sr, who probably had a rational point of view on the subject and might have given Bush useful information. No, he meant his Father in Heaven. So the final decision on Iraq was the result of Bush consulting with a mythological being. I suppose this was meant to give a lot of his constituents confidence that he was doing God's Work. It should be scaring the hell out of all of us.