I suspect the church shooter is a result of the Trump-is-Hitler preaching from the Left. The Left is infusing its rabid base with the idea that the Left is literally being attacked and the Left should push back with “equal” violence.
The left has stirred up its crazies during every Republican administration since Nixon. This is how they always respond to the loss of power.
But I agree with your point. The left owns this. Just as Obama created an environment where cop killing became a crisis, the left’s hate for Christians that supported Trump could be responsible for this.