Good ol’ Al-Taqiyya. Lying to the infidels, muslims can lie and say they are Christian if in their hearts they still are muslims.
No offense, but who makes this kind of huge mental mistake? I have never gotten so rushed in speaking about my Christian faith, that I called myself a muslim. He wasn’t even speaking quickly or looking really stressed out. He was just answering a question and this kind of flub happens?