I went to a Unitarian church once. I am not a religious person, but it struck me as completely devoid of any concept of God. It was just a bunch of liberals with nothing better to do on a Sunday morning.
I agree with everyone that this was a terrible act. But for those of you who do not want to drag religion into this, just wait. If the shooter is found to be a member of a Christian denomination, especially a conservative one, the MSM will instantly turn this into a direct attack by that denomination on the Unitarians.
That dog won't hunt here. The churches in East Tennessee have a long history of pulling together especially when one is in trouble. For example if one church burns you'll see another one offering them worship space. There's no denomination fights here. None for over 100 years have been purposely singled out and harassed by another as far as I know. A preacher might speak against another denomination in the pulpit that is as far as it goes. The area is highly diverse and most of us have multiple denominations in the immediate family.