The Religion Conundrum

The founders of many major religions claimed that they communicated directly with God, who dictated to them the scriptures they wrote. Others claimed to be God himself, born in human form and, therefore, the authors of God's word. However, if there is only one God (and there has to be only one God; otherwise, the followers of different religions would have different DNA and other building blocks of the human body), why would he give different messages to followers of different religions? 

Think about it.