Umm, just to translate that surah a little:

To every one of (the religious communities "of the book," Muslim, Christian, Jewish and Sabaean) (God) appointed a (distinct) law and way of life. If God had wanted to, God could have made you all one community, but instead(did otherwise) in order to test you by means of the (spiritual guidance) he gave you (in scripture). Compete with one another, then, in doing good works (based on what you were given)! Ultimately you must return to God (in the afterlife) and then God will make you truly understand the matters that you characteristically had differences about.

By the way, this is a good piece of text to know if you're ever debating with an al-Qaeda type who thinks Islam will inevitably take over the globe. Kind of pulls the carpet out.