"...that a real god unknown to you won't punish you for following a false deity?..."
Such a diety would not decieve people by using a humble man who rode a donkey into a city and who spoke in such parables. But you would have to have logic and a heart to understand that.
Then why would your diety decieve people by allowing hundreds of different denominations that claim to follow him exist? Each claiming the other sectarian will go to hell and the common man left in the middle with no objective means to tell them appart?