Are you saying that because they were practicing a form of Christianity that you don't like, it was okay to arrest them? Simply because in your opinion they were presenting a bad image of Christianity?
No, not at all.
If Group A has 10,000 members and has reserved a public space for a program, and group B with ~10 members descends upon them and creates a distrurbance, what would you expect?
Would you expect the police to force the 10,000+ to allow the small group to disrupt the planned festivities? To ignore the bullhorn, flags and chants? I would expect the police to present Group B with an alternative of either leaving, or facing arrest.
If this were a Christian gathering of 10,000+, and a dozen or so Athiests descended upon the group and began insulting the Christians, what do you think would happen? Typically, the disruptors would be given the same alternative these Christians were using.
IMHO, Christianity had little to do with the motive of these individuals; this was a power ploy for attention using Christianity as an excuse. These actions had very little in common with the teachings of Jesus Christ.