How is anyone stopping them from practicing Christianity? Has anyone been barred from a church, arrested for praying in a church or at home?
You qualify this statement with only 2 locations – church or home. The fact is that the government has no right to bar your practice of religion anywhere including public spaces.
So anyone can claim any action to be part of their religious practices, and it must be accepted regardless of what their own doctrines and holy texts actually say?
Are you sure you want to open THAT door? Many Wiccans believe their rituals should be performed "skyclad" (meaning naked). If your school led prayer should not be stopped, why should their skyclad rituals be stopped?
There are a few problems with this statement. First – no one here (at least AFAIK) has called for SCHOOL LED PRAYER – that is a straw man. There is a valid argument against having government officials representing the government (as a public teacher is) leading a prayer session. That is not what is being discussed though. Rather it is your ability to express your religion in whatever space that you wish to which you have a right to do.
Second – yes, anyone can claim whatever they want as part of their personal religious doctrine. That wall that you are so fond of requires that. Just like religions don’t have a right to demand that you practice one of their tenants, you do not get to define what the religious tenants are for that religion. A wall works both ways. Further, for you to demand that their religious tenants say something different is insanely arrogant. You cannot waltz in dictating what a religious text actually says when you don’t have faith in it to begin with. I can’t fathom how you can claim to understand what the ‘true’ tenants of a faith are when you are not of that faith.
Lastly – we DO want to open that door because it is already open. What you don’t seem to understand is that your religion does not give you carte blanche rights over existing laws. Those laws that might make it illegal for you to dance around naked in a school ARE NOT AGAINST RELIGION and therefore perfectly fine. No one is allowed to dance around naked in the school for other reasons completely separate from religious freedoms. You also don’t have a right to sacrifice a virgin to your pagan gods either – it violates others rights. What you don’t have the right to do, however, is demand that students cannot pray in a school setting or hold group prayer at an event because that IS specifically violating religion. It is not a rule or law that is aimed at some public interest, safety or protection of others rights. It is solely there to infringe on others ability ‘freely exercise’ their religion and it is wrong.