While the Bhagavad Gita embodies orthodox Hindu belief, there is considerable flexibility in the interpretation of this belief. In my view, the Gita sets forth pathways to the achievement of goodness which leads to complete happiness. Such goodness brings us revelation and release from the cycle of birth and death.
There are several pathways to become totally good and to attain the bliss faithful Hindus presumably seek. They all result in detachment from the material world and a merger into God. This merger can be achieved through devotional worship, or through pursuit of knowledge, or through performance of good deeds.
The question remains as to how God is defined. What is that which starts out as a spark within us and ends up as the God whom we absorb or who absorbs us? In the Gita, The Lord Himself provides extensive explanations as to who He is, but in the end the explanations are so inclusive as to become just about everything. God even tells us He is everything, though everything is not God.
It is often said that journeys are not about reaching a destination, but about the journey itself. But the journey of life cannot be meaningful without a destination and for believers the Gita gives meaning and to both.
For more information, check out Irina Gajjar’s book The Gita at http://irinaspage.com/philosophy/the-gita-sacred/