Some people, atheists in particular, are fond of claiming that God is unnecessary for the existence of morality. This is sheer fantasy.
Without God, "morality" is nothing more than a man-made construct subject to the whims of our fickle attitudes: such-and-such a behavior is taboo now, but wait 20 years and it'll likely be acceptable. Or something like that.
The existence of God, however (the Biblical God, that is), is a game-changer, for He has clear, definite ideas about right and wrong that aren't subject to our ever-changing tastes.
God, being who He is (including our Creator), has the right to define proper behavior and proper motivation. Without God -- without Someone to tell us what's truly right and truly wrong -- life becomes a free-for-all in which every person decides for himself what's "right" and what's "wrong." In other words, without God it all becomes subjective. ("Just because something's wrong for you doesn't make it wrong for me." Sound familiar?)