Muslims do not keep the name Abdul Masih. It is the biggest blasphemy [shirk], nor do they keep tattoos. You have a stupid view of people and religion. People do not behave this way because of religion. They use religion as a tool - culturally, socially, or politically. Example, Hindutva lynch mobs chant Jai Ram. Such people have nothing to do with Ram, Jesus or Allah. Among some people usage of religion became embedded in the culture. Christians from the Middle East have the same civilization culture that Muslims in the Middle East have. It is only that there are far more Muslims now. Had the situation been reversed there would certainly be a lot more violent 'Christian' extremism in the Middle East. Needless to say, Muslim nor Christian behave this way because of religious reasons.He was a Muslim refugee pretending to be Christian, just like the refugee who tried to blow up a maternity ward in Britain. Who on earth would shout "Jesus is great" on a killing spree? sounds like something a rabid brainwashed Muslim terrorist would do to prove that "look Christians do this too this is Christian terror yada yada!".
Eyewitness accounts, he was probably some refugee who pretended to be a Christian convert in order to get asylum.