For a Christian, it is what they believe that makes them so, even when actions don't align. That's not how an a-unicornist constructs the world.
Perhaps, I can't speak for anyone else, but for me, belief IS doing so...
Not sure which one begets the other though....at times it's hard to pin point if belief is first and doing second or of doing is first and belief second.
I believe in love so I love, or do I love and then believe in it?
Not sure if there is much difference in practical terms though.