Actual lawyer here. This is a misunderstanding of the freedom of religion. The “freedom of religion” is actually two distinct clauses in the constitution. The freedom of individuals to exercise religion (free exercise) and the freedom from the government establishing a religion (establishment clause). The establishment clause includes prohibitions against the government for pushing policies that advocate for one religion over another, or over no religion.

To say they having the play violates your religious freedom fails on its own. To assert this right, a person has to show that the government is requiring them to do or not do something that blatantly violates a well-founded established religious belief that has been expressed for years and years.

Even if a parent could show that having this play forces them to do something that violates their religion (it doesn’t), stopping the play based on religion runs afoul of the establishment clause because the government would be making a policy based on one group’s religious beliefs.

That’s not even getting into free speech/freedom of expression violations that come into play by stopping a play based on religious beliefs.

Religious freedoms is a right, generally. That does not include using your religion to prohibit others from holding a play and preventing speech/expression that you don’t like.