Well the idea that we worship a different God is really a question of degrees. In a sense, we all worship different Gods until we stop worshiping ourselves and focus on the Uncreated being as the priority of our lives.
I can understand how theologically one could argue that we worship different Gods based on our presumption that God is how he has revealed himself in the Orthodox Church and those who don't know him in his own body can't really "know" him. However, we also have to remember that God loves the whole world, so much that he sent his son Jesus Christ to die for us on the Cross and unite us to him, and that the Holy Spirit blows where it wills, to bring people to this truth. In this understanding, how can we say that people who pray to "God" are not being heard by the same God we know we are addressing when we say our prayers? There is, after all, only one God.