At the time, I was a Jehovah's Witness (I had been baptized as a full member when I was in 9th grade). I was an active member, and during this time frame, I spent some months as what was then known as an "auxiliary pioneer". I was not ashamed of my beliefs and while I tried to respect other people's desire not to be harassed by evangelism, when asked about them I shared them freely. A variety of things happened a few years later to convince me that the beliefs of Jehovah's Witnesses are entirely wrong and quite evil, and I disassociated myself when I was 25. But at the time of these events, I viewed blasphemy as a really serious issue. [ETA: Albeit one which God was responsible for dealing with, beyond organizational enforcement through shunning.]
Because Piss Christ involves a crucifix, and because I, as a JW at the time, firmly believed that Christ was murdered on a stake, not on a cross, the particulars of Piss Christ, while somewhat appalling, were not regarded by me as blasphemous in the same way they presumably were perceived by, say, Catholics. But it was interesting to me to see people who were otherwise Christmas-and-Easter Christians suddenly get Real Excited about something somebody did in the art world. As a member of a religious organization that worked hard to _set_ precedents about religious freedom (such as conscientious objection to military service including alternatives acceptable to SDAs, the right to refuse medical treatment such as blood transfusion, the right to go door to door), I found something about this very darkly humorous. Ha ha ha, you never had any issue treading on me, now look what somebody did to you. Tee hee hee.
Piss Christ has been a focus of religious anger, and accusations of blasphemy ever since. It has even come up in conjunction with the film, Innocence of Muslims.
But as far as I know, Piss Christ, while the target of vandalism in reproduction, has never been the focus of killings and hostage taking.
Tolerance in our society is meaningful and widespread. Let's continue to be uncompromising in our tolerance. Self-defense is an excuse for violence. The defense of others against violent assault is an excuse for violence.
Blasphemy is no excuse for violence. Suggesting that blasphemers who are targeted by the violent are in any way to blame for what the evildoers have evil done, is on a par with blaming a rape victim for wearing the wrong clothes, being in the wrong place, or just being a woman.