You want opposition?
Just for a second, let's forget all the missionaries, crusades, and exclusion that religion harbors.  Now, let us focus on some of the GOOD that religion(specifically Christianity, as it is the religion I am most familiar with) can do:
The Poor-
As a nation, we have decided to let our poor starve in the streets for the most part. Religious organizations provide food, run shelters, and help those who have been knocked down get back on their feet (jobs). In this case, religion provides a vital service to those who are less fortunate.
Peace-
Regardless of your interpretation of the Bible, it is impossible to deny that Jesus did not preach peace. While certain groups have violated it over the centuries, the peaceful actions that Jesus  commands his followers to use present a very effective model for waging peace on the world.
I will return with more, but I am going to bed. Adeau, worthy adversary.