What is interesting about Blasphemy Day is that those who are celebrating cannot, despite their best efforts, increase the level of their blasphemy. Their unbelief already constitutes blaspheming to the superlative degree. Whatever tiny Blasphemy Day rituals they perform (such as trading their souls for cookies) are in the noise.
God cannot be any more angry at the happy blasphemers than He already is.
The wrath of God is being revealed from heaven against all the godlessness and wickedness of men who suppress the truth by their wickedness (Rom 1:18)The word translated as 'wrath' suggests intense fury. God is furious with those who suppress the truth—i.e., unbelievers. God is not going to be "a wee bit more furious" because you mock him in a song, a painting or a board game. Your crime is already a capital offense—and you can't get sentenced to consecutive eternities, or eternity plus a few millennia.
The free-speech reasons given for Blasphemy Day are, at least in most of the world, totally bogus. You know that, I know that, and atheists know that. In the U.S. people like PZ Myers can blaspheme (or, more accurately, conduct activities that he perceives as blasphemous) 24/7 to a large audience. He doesn't get arrested. He doesn't get fired. His right to free speech is unhindered. If some nutcase harms or threatens him, it would be a crime, not state-sponsored retribution.
The actual reason, everyone knows, is to mock religion. Hopefully to piss off some of the religious—which has indeed happened. This is cage-rattling, pure and simple. In my opinion the appropriate Christian response is not to get angry over Blasphemy Day. It is either to ignore it or to treat it with a kind of detached bemusement. Remind them that what they are doing has no effect on their eternal soul. Something like:
Unbeliever : Basphemy Day Activity :: Hitler : JaywalkingAnd who cares about mocking? Mocking is perfectly acceptable and, if clever, which it usually is not, can even be funny.
Mock away. I don't require that atheists "respect" my religion and refrain from mocking me or it. After all, fair is fair: I certainly do not respect their decision, which I see as a cosmic folly, and I am not above mocking atheism from time to time. The only truly important issue is the freedom we both share to practice our beliefs or nonbeliefs. There is no need for us to respect one another's beliefs or nonbleliefs, or to refrain from mocking. I certainly won't cease and desist mocking unintelligent arguments from the likes of Jerry Coyne or Russell Blackford, or the total nutwhackery of a (atheist award winning) Bill Maher or a Sam Harris.