Niehbur's famous book was published in 1944, and reminded Christian leaders that evil did exist, and pretending it did not exist would only lead to it's triumph...
A similar critique is found in today's Wall street Journal, showing church leaders who promote pacifism while ignoring the reality of evil...
there are true pacifists, but alas too many who claim to be pacifists have never confronted evil.
I once had a conversation on line with a Pastor who was a radical pacifist, who said he would not kill even to defend his own life...
Ah, I wrote back, I agree...but when I was in Zimbabwe, the guerillas attacked a Protestant mission run by a pacifistic British church...they did not simply kill those there, they tied up the men and abused the women (including the 13 year old daughter) first before killing them...
He wrote back and said he would not kill even to defend his daughter...
My own reaction was different.
When I came back to the US, I learned to shoot a gun.