This is known as the "No True Scotsman" fallacy.
Doesn't really matter if they're "real" Christians or not. They go to church and they vote.
No it is not. As it’s written, you shall know them by their fruits (Matthew 7:16). One who calls oneself a Christian is not necessarily one, but lying to you and probably lying to oneself. It is not “illogical” to expose a fake Christian (2 Corinthians 11:13).
Going to church and voting does not make them Christian either. That’s the red herring fallacy.