“The Constitution prevents the Gov’t from creating a state sponsored church...”
And what does that look like when it is happening?
It looks like congressmen voting on a proposal in the house, and then sending it over to the senate for debate where it is voted on there as well. Then, once both house and senate have voted in favor of the proposal, the affirmed bill is sent to the president for his signature (or veto). Once the president signs it, then voila, you have an official established religion. Depending on the implementing legislation, other religions would lose their tax exempt status, or their property confiscated, etc.
It doesn't remotely resemble a high school using a church facility to hold its graduation ceremony.
The Gov't takes your tax money, and gives it to a particular denomination. The church clergy are Gov't employees, with full benefits, and the property the church sits on belongs to the state. The state then dictates the message set forth by that church.