Religious Discrimination

I can't understand why athiest groups are so intent on trying to rid our society of religious symbols, events, and other practices of one's faith, in particular, Christianity.  What is the true motivation?  Why should they really care if a school conducts prayer before the start of class, or perhaps places a Nativity scene on school property.  Does it really offend them that much?  Do they really think that "Christians" ultimately want to take over and control every aspect of their life?  What is the true motivation for actions and behaviors of athiests?  I think it is as simple as this...I will pray for them and if they are right and I am wrong then their life is unaffected.  If I am right, and they are wrong, only good can come there way even though they may not be attuned to it.  What are they afraid of?  What is their motivation?  Is it possible that they are perhaps being led in part by another force that wants nothing more than a complete surrender of any and all Christian beliefs?  Most Christians will respect the beliefs of the athiest but athiests do not reciprocate?  Why is that?