Brahman and Ishvara are sometimes referred to as "God 1 and "God 2" or nirguna Brahman (God without attributes) and saguna Brahman (God with attributes). The former is pure consciousness, while the latter is consciousness associated with maya. Figuratively speaking, Ishvara wields its maya like a spider wields its web without ever getting tangled in it. The spider is both the intelligence and material behind its web, and while the web is the spider, the spider is not the web. Similarly, Ishvara creates the world out of itself but never becomes its creation.
Although Ishvara is often described as being omniscient, omnipotent and omnipresent, Ishvara isn't a person with superhuman powers. Ishvara also doesn't reside in any specific location because Ishvara is all that is, including these very bodies and thinking minds. Ishvara is best defined as the creative principle, that is, both the intelligence and matter used to form and maintain the universe. To personify Ishvara then, is strictly a personal choice, much in the same way it’s a personal choice whether or not to call the third planet from the sun, "Mother Earth."
Ishvara is often devotionally referred to as "Bhagavan"—the one who has bhaga or the six-fold virtues in absolute measure, which include: total knowledge; total dispassion; total capacity to create, sustain and resolve; total fame; total wealth; and total lordship.
Seekers might wonder why Vedanta, a wisdom tradition based on logic rather than belief, even bothers with God. The assumption might be that any mention of God is due to Vedanta's historical roots and not of any real value when it comes to gaining freedom. In short, God is equated with religion. But Vedanta would argue that such a view is too limiting and would ask how can we deny this worldly experience and come to terms with it without an understanding of God? Knowing who/what I am isn't enough. In order to be free, we must also put some definition to that which, as individuals, we experience on a daily basis. Otherwise, we run the risk of understanding who we are but at the same time, misunderstanding or even resenting this world in which we must transact. So, understanding and even showing devotion to Ishvara has purpose, and isn't just mindless worship. Furthermore, if you listen to Vedanta's logic, Ishvara isn't something to be believed but rather to be known. It's only with knowledge of Ishvara that we, as individuals, can attempt to live in harmony with that which engulfs us.
Ishvara’s roles can be summarized as (1) creator-sustainer-resolver of the universe (2) governor of the field of experience and (3) benefactor/giver of the fruits of action.
Ishvara as creator-sustainer-resolver
Ishvara is sometimes compared to a cosmic being, changing its name depending on the stage of manifestation. First, is Ishvara (with no name change) as the unmanifest deep sleep state when the universe is in its seed form. Next, Ishvara is referred to as Hiranyagarbha during the germination state or dream state, which involves the first tangible manifestation of the universe. Lastly, Ishvara is referred to as Vaisvanara during the waking state representing empirical reality. After some time, the universe dissolves and Ishvara (representing all three states) goes back into a deep sleep state again, only to repeat the other states in a perpetual cycle of sleep-dream-waking. (For more about creation, Shankaracharya explains in detail the various phases and building blocks in his book, Tattva Bodha.)
Ishvara as governor of the field of experience
Another important role of Ishvara’s is establishing order. For any system to work, there must be a set of rules governing it. Figuratively, Ishvara ensures this by always doing what’s in the best interest of the Total. If we analyze Ishvara’s order we find not only physical laws, but laws that specifically apply to the individual, such as psychological and moral laws. In order to live a relatively peaceful life and avoid unnecessary pain, it pays to understand the rules and see the value in them. Ironically, animals needn’t concern themselves with such matters because they simply follow their innate programs. It’s only human beings, with their keen intellects, that need to be reminded that this is a lawful universe.
In many ways, Ishvara is like a giant super computer with all its myriad of programs running simultaneously. One of those programs is the jiva-program, which brings us to the question of free will. From the microcosmic level, we obviously have the free will necessary to fulfill certain needs and much more. But from the macrocosmic level, the world is like a giant video game with everything already pre-programmed into the system. Furthermore, Ishvara (as pure intelligence/knowledge) knows exactly what’s going to happen today, tomorrow and every day into infinity. So while it’s important for an individual to do what they can to gain knowledge and modify certain unhealthy tendencies, ultimately, Ishvara is the doer. This is a profound truth that Vedanta helps one to realize and is the reason why knowledge of Ishvara is so important—because without having a grasp of the big picture, liberation is really hard.
Ishvara as giver of the fruits of action
Being both creator and governor of the universe, Ishvara is also the giver of the fruits of action. Whatever action I carry out, Ishvara, as the field of experience, is sure to respond—if not immediately, sometime in the future. If my intentions go against the universal laws, I will suffer the bitter fruit of my actions. Likewise, if my intentions are in harmony with universal laws, I will enjoy the sweet fruit of my actions. Scripture implies that in order to cultivate sweet fruit, it’s necessary to plant the right seeds. Thus, the individual might see themselves as a farmer sowing seeds, in the form of actions, in order to later reap the sweet fruit.
That thou art
In spite of the many enumerated glories of Ishvara listed in the 10th chapter of the Bhagavad Gita, Vedanta reminds us that Ishvara and jiva’s (the individual) only apparent distinction is their upadhis. An upadhi is a limiting adjunct that through superimposition, makes something appear to be that which it is not. The classic example is how a blue cloth placed behind a crystal make the crystal appear to be blue. In the same way maya is the upadhi of Ishvara, the body-mind-sense complex is the upadhi of jiva. Both upadhis hide the truth that Ishvara and jiva are in essence, awareness. Thus, we can conclude that:
maya + awareness = Ishvara
a body-mind-sense complex + awareness = jiva
This is best summarized in the mahavakya (great saying), tat tvam asi—“you are that,”with “that” being Ishvara. In other words, Ishvara and I, are one and the same and any difference is just an appearance. The body-mind (essentially, the five basic elements in gross and subtle form) is a product belonging to God, while awareness is the substrate of all being.
In the end, we find that the entire world exists in me, including the apparent person and Ishvara, because in essence, I am non-dual awareness—that which everything comes out of and resides back into. Thus, there is no difference between me and Ishvara. The objective for the seeker is to then see that it’s all one operating system.