Coral, good question... here is my opinion... the Bible would like us to think about the issue of love/hate... it seems to contradict, but in my mind i see more of a circular cycle... we develop love for God and goodness, knocked back again by evil and harmfulness... to connect agian with love, with re-newed strength, o face again the evil..

it is a spiral in ways... building strength, feeling weakend, building strength, being weakened...

the point is, each time we build strength, we weaken the Devils position...

i agree, Satan serves a purpose.. to aspire us to reach higher each time we fall...

eventually, we build enough strength that Satan loses his grip on us...

evil is represented in other religious texts... i, myself, prefer not to be penned in by only reading and learning from one text... forgotten knowledge is still useful... and, imo, preferable... just some basic beliefs, that good is good; bad is bad.... why complicate it?