Genesis being the first book of the OT and laying out when God created all things seems like the perfect place,the only place where we would be told about the holy trinity,from the very begining so as to avoid any confusion later on,for instance,we are told that God created Adam,the first man in the first 6days,surely somthing as important as the Holy trinity would be mentioned,it is,after all,The most important of all the scriptures,it tells us that God was the creator and created man in his own image,created a female mate from Adam and so began the human race. Without the human race,All the other creations of God would be meaningless,they would be un named,(Adam named all creatures),without the human race there would be knowone to worship God! Surely the father,son and Holy Ghost would be revealed to the first humans,Adam and eve,so they could decide( free will) what to belive and what to pass on to there children and ultimately the rest of the Human race for all eternity??