At the federal level, if the targetted victim or victims were targetted for their religious beliefs (including what the perp may believe to be unfairly judged by a Christian church), that IS a hate crime.
A hate crime is a crime motivated by bias against race, color, religion, national origin, sexual orientation, gender, gender identity or disability. Learn more about hate crimes in the United States.
www.justice.gov
The state of TN defines it exactly the same way:
"A crime committed by a perpetrator who
intentionally selected the person or the property that was damaged or otherwise affected by the crime, in whole or in part, because of the
perpetrator’s belief or perception regarding the race,
religion, color, disability, sexual orientation, national origin, ancestry, or gender
of that person or the owner or occupant of that property."
Understanding Hate Crimes: Definitions
In this case, the mass shooting of Christian people in a Christian school, has not been designated a hate crime.
Personally I find that incredibly bizarre.