It stems from a contradiction that caused great internal angst and unrest, yet could never be brought out to a satisfactory conclusion.
The issue is when those that are Christian brothers condemn one source of evil while supporting another.
An example would be the condemning of Islamic terrorism while applauding the mis-treatment of Palestinians by Israel.
I cannot minimise the effect this has had on me internally, and the effect that I believe it has had on them. It is an insidious evil that has seared the consciences of otherwise good men and made them the helpless tools of wickedness in those aspects of their lives. I believe it has blinded their eyes to the plight of the poor and helpless and hardened their hearts to suffering caused by the regimes they support.
In the Christian walk it is difficult to live the black and white reality of absolute good and absolute evil, yet we must learn to distinguish between them. This also has implications on how God works and walks with us, but those are thoughts for another time.