In many, if not all MLB parks, there is a song played at the 7th inning stretch. The song, "God Bless America" is offensive to all other religions and atheists as well.
MLB parks rely on public infrastructure and even public money to build the stadiums, that makes them partly government property and it is against the constitution to endorse one religion as a violation of the 1st Amendment and violates free speech.
Demand that MLB stops this unfair and (probably) illegal endorsement of (the Christian) religion at all ballparks.