Why do religious people believe birth control is wrong?

Say a woman is in a married, monogamous relationship. She has had several children, but wishes to have no more. Now, lets say this woman has been brainwashed by the church to believe using all forms of birth control (except planning around her menstrual cycle to reduce the chances of pregnancy) is evil. What led to the church feeding people this belief? Is it because they want women to be baby factories? Nothing but broodmares to produce children who will, likewise, be brainwashed into the church?