Deen 
  oth ayah clearly state that it is DEEN. On the other hand, in the second ayah, Allah also address other beliefs as deen as well. So taking Islam as deen alone is not good enough, for we are to proclaim it above other deen. *s*

Therefore if one is to defined religion, the DEFINATION OF RELIGION, no matter how and what constitute the defination, will only fit Islam while the other beliefs disqualify. If the defination qualifies all beliefs, good chances are, Islam does not qualify, for Islam is more than that defined religion.

If the defination qualify other beliefs and Islam too, then the defination is inaccurate and definately wrong. Why? Because it implies that in having a religion, one have alternatives to choose, of which one is Islam. It also implies that you are not good enough a muslim as well *sad*

The simplest, religion is define as ISLAM, else disqualify *grin*