Those who are bent on threatening other people in the name of “God” are mentally ill (or unstable) because they have crossed the line of civil and rational discussions. The kind of God that they subscribe to is merely a projection of their dark side/ego/shadow self – one that is vengeful, hateful and condemning. I think one main reason why they resort to threatening others in the name of God because of religious indoctrination in institutional churches that paint God as mean and vengeful. I came across the following comment in a website below.
“Like many religious fanatics, religious fundamentalists believe they have or deserve special rights in society, above all others, because they alone are God’s chosen people; that their ‘truth’ is the only one and so right that it must be forced onto others at the point of a sword (see previous list “Victims of the Christian faith”) and that anyone that disagrees must be persecuted and even killed, exactly as their philosophy prohibits. This is the definition of mental illness.”
So, there is a place for keeping a safe distance from people who threaten others in the name of God because they are crossing the boundary of civil discussion. It is one thing for people to have disagreements which is part and parcel of any discussion, and it is another thing for people to come across as condemning towards those who don’t agree with their views. So by keeping a distance from such people or institutional churches, we are applying wisdom and discretion to protect ourselves from further condemnation and threats by them.
“Belief in a cruel God makes a cruel man.”
Thomas Paine
The Mystery of Christ 
Could this be considered a “threat by proxy?” Do as I say or God will punish you! Whatta’ load of B.S.
Yes, and it looks like this is a form of cowardice too, if people resort to threatening others in the name of God instead of engaging in a rational discussion just because others disagree with their doctrines or viewpoints.