You're wrong on multiple fronts. Christian churches do a lot of good in the community. They have 10 step programs. They help unwed mothers and refugees. They have counseling for people recovering from grief or sexual abuse. They provide money to the poor within the church. They collect money and food for the poor within the community. Some churches run food banks. Most support foreign missionaries.
And even if they contribute nothing to the public good they have a constitutional right to exist. They don't have to convince anyone of their right to exist and manage their own resources without being robbed by the government.
It's really unfair to single out churches as nonprofits who don't serve the community. Environmentalist organizations are notorious for doing nothing but filing lawsuits and hosting expensive parties for themselves and their wealthy donors.
A Supreme Court ruling early in America's history ruled that "the power to tax is the power to destroy" which is just one reason churches aren't taxed.
Equating every church as being like the one run by Joel Osteen is unfair too. I've never attended a church where the pastor and/or his wife had their own private jet. The average church in America has 100 members. Most pastors aren't well paid. Very few have adequate retirement savings for their pastors.
Governments at all levels waste incredible amounts of money. I see no reason whatsoever for them to get any more money than they already do.
I agree most churches don't remotely function like a mega church. As a result, some actually serve their communites well. In America, all places of worship have the right to exist as far as I understand. I agree the less money in government hands, the better. By how social media was used in this instance, it served as an effective counter balance to shame Osteen into assisting the very community he was willing to accept tithes and offerings from.