Hmmm. To paraphrase Donald Rumsfeld, there are known evils; things that are evil that we know are evil. There are unknown evils; things that that are evil that we do not know are evil, because they have yet to manifest themselves. There are known unknown evils; things that are evil we have considered. And there are unknown unknown evils; things that are evil we do not know are evil, because we have yet to consider them. Evil is insidious, and even in your utopian New Jerusalem (scriptural citation required) will doubtless invade if it can. Most likely, it seems to me, through the attitudes of the self-righteous.
Best wishes, 2RM