According to Sam, God's name in Latin. Speaking it to a possessed person make her flinch.
In truth, God in Latin is not 'Christo', but 'Deus'. 'Christos' would be 'Christ' in first century Greek, translated from the Hebrew 'Moshiach' (English: Messiah) both meaning the 'Anointed One'. It was modified and changed by the Romans into the Latin 'Christus' meaning Christ, or sometimes mistakenly 'Chrestus', the 'Marked Man'. 'Christo' could arguably work to the same effect as was depicted, literally Latin meaning 'by/in Christ'.