A Christian's urge to evangelize stems from the joy of having found Christ. Having discovered the truth, he simply wants the whole world to know. The urge is spontaneous and entirely unselfish. It is not wanting to impose your beliefs on others. And it should never be judgmental. Thinking that you are saved and those who do not listen to you are lost forever is totally out of place. Protestant missionaries entering Catholic countries to convert Catholics, believing that all Catholics are lost, are all misguided because they don't realize that they are actually breaking up the body of Christ! The "original sin" here all originated with Martin Luther who began the Protestant Reformation.