"I just don't see a valid point"
Then I suggest a good Critical Thinking course... because it can't be stated any plainer than the url I already posted, why it's a flawed concept.
"A common one which is often heard when a religion or religious group is criticized is:
3. Our religion teaches people to be kind and peaceful and loving. Anyone who does evil acts certainly isn?t acting in a loving manner, therefore they can?t really be a true member of our religion, no matter what they say.
But of course, the exact same argument can be made for any group ? a political party, a philosophical position, etc.... "
If you need help understanding that, then you need more help than I am willing to give....