When I feel that the t-shirt I just bought is the best t shirt in the world, I am free to believe it and live with it and it is none of anybody’s business. 
When I say the t-just i bought is the best in the world in front of 10 other people all wearing different t-shirts, I am no longer talking to myself and my statement is now open to criticism and debate. 
Same goes for religion. 

Declaring beliefs and being closed to discussions would only make the people doing it believe that they live in a world where the right to own and judge/rate a “t-shirt” is only theirs.