Thanks [MENTION=7635]Remathilis[/MENTION], thats about how I look at it too.
[MENTION=6777974]Aribar[/MENTION], well in game there have been several quests for "divine" magic that could do things to resolve the plot, cure disease, raise dead, etc. So in my campaigns there has been the two sides of magic, with some casters hitting the gray area.
Another example was a wizard that could heal, but he had to use life transference or necromancy spells to do it. So he was looked at very suspiciously. Cause ALL the peasants KNOW that healing comes from the gods..."duh" says the peasant.
Out of game, it was likely so that the "roles" wouldn't be infringed upon. In much literature, especially today and in video games, people may specialize but there isn't normally such a divide. In some of the final Fantasy games I created Blaster/Healers.
I agree that there is no longer any rule dividing them as such (other than spell lists). I will likely keep them kinda separate however, much like Remathilis says up thread.
Of course in 5e, my white wizard society will have the magic initiate feat, instead of me arbitrarily putting "cure" spells on their spell list like I did in 1e.