Not sure if this question belongs here, but most of my readings include this line and I'm not religious so I have no idea why people would want to fear a supposedly benevolent creator - my notions about this are vaguely along the lines of something about fear of a deity will keep you in check, morally and spiritually?
This is simply an issue of changing meanings. In this context, it doesn't mean fear as in "be frightened of" but, as the OED puts is:
To regard with reverence and awe; to revere. Now only with God as obj.; formerly in wider sense.