We begin with the Name of Allaah

The similarity between Shia rituals and Christian rituals

While it is not a prevalent practice among Christians, look at these pictures of Christians in the Philippines practicing the same self flagellation tactics practiced by Modern day Shia. 

Notice that this practice goes back to early Christianity and outdates the practice of the shia --who most probably took it from them. From the fourth century AD, flagellation was practised by both clergy and non-clergy as the most effective means of penance. (See the New Encyclopedia Britannica, Vol 4, Micropaedia, p 813.)