To summarise the conclusions of Bhagavad-gita it may be said that,
1) God is one and everything is in Him and He is in everything.
2) To render transcendental service unto God is to serve everything that be, just like to water the root of the tree is to water the different branches and numerous leaves of the tree or to supply food to the stomach is to vitalize all the senses and the sense organs of the body.
3) The parts are automatically served when the Whole is served but when the parts are served the whole may not be served or not served at all.
4) The parts and the Whole being eternally related, it is the eternal duty of the parts to render service unto the Whole.
5) A recipient of the services of the parts, God's sat-cit-ananda vigraha i.e. the all-attractive Cognizant and all-blissful Personality eternal. He can reveal Himself by His own potency without any help of the external potency called maya in order to be cognizable by the limited potency of the parts and as such He is not only the greatest of all but he is the smallest of all. That is His prerogative.
6) He is better realized when He by His causeless mercy agrees to descend in this mortal world but he He is never realized by the partial speculations of the empiric philosophers however systematic and long-termed it may be.