Killing in any context is abarbaric act that violates every human being right to live. I may only accept killing of those who commited homicide not only as punishment but to make sure less killings would be commited later and this to be conducted by a fair and strict judicial system.
On the other hand, beheading people for religious considerations is far worse than for political ones because religious groups don’t kill only as a sacrifice but as punishment for what is considered by them worthy of killing like disbelieving, adultry, homosexuality. Moreover, at times of religious clashes members of each group coldly and wildly kill other groups’ members. The killing is done by anyone without even a trial. I red once that the largest number of wars and casualties throughout history is that of religious conflicts.
I agree that killing for religion is based on "faith" or the lack of it, but then again so is a revolution. Although when revolting, the oppressed are removing the source of that oppression, but yet that action is ultimately based on an idea or belief that life will be better after the revolution. So in the end it seems that both actions are based on faith or belief (or the lack of that faith or belief).
I don't believe that both are based on the same kind of faith, for not only the belief that life would be better after revolution doesn't necessarily incur killing. Moreover killing in religion is more of punishment and revenge even if a better life later doesn't require killing.