Do blasphemy laws damage freedom?

I would say any law restricting religious freedom, including the right not to be religious, is unacceptable. In the words of James Madison, Father of the U.S. Constitution and 4th President of the U.S., "The purpose of separation of Religion and Government is keep forever from our shores the ceaseless strife that has soaked the soil of Europe with blood for centuries". Laws like the one to which you refer are fuel to that kind of fire, and the world today doesn't need any more.