If it was God, we would know. Your little insult tyrade against Christian people serves no purpose, my friend.
But this is exactly the whole point of the thread. You wouldn't necessarily know.
Many many people who have suffered from Schizophrenia and believe whole heartedly that they are in fact hearing the voice of God.
I would much rather have everyone who hears voices head to a mental health facility for a check up than have them do exactly what the voice says.
I would guess that if you authentically heard the voice of God, you wouldn't mistake it with schizophrenia, but the opposite is not necessarily true. That's very scary.