There is not only truth and falsehood, right and wrong, good and bad.
When it is understood that purity of truth and purity of falsehood are theoretical constructs, a reality is revealed in which some things are partially true and partially false, and other things are neither true nor false. Going beyond this, it is possible to comprehend that truth itself is a theoretical construct, and a more profound reality in which there is no truth, but some things are not un-true, other things are partially un-true and partially not un-true, while other things are neither un-true nor not un-true.
It is difficult to explain the fundamental concepts of Yoga in binary terms - and such "black and white" thinking is actually contrary to the practice of Yoga. It is very similar to how showing someone a two-dimensional picture of an "orange" is nearly meaningless to someone that is able to see the world in only black and white.
Krishna said that the limitations of binary logic confine a person's thinking to concepts of identity. Identity is contrary to the practice of Yoga. Identifying something as "this" requires identifying other things as "not this," and such thinking naturally results in desire for preferences. And expressing desiring what is preferred, and aversion for what is unpreferred. Desire and aversion result in aggression, to obtain what is desired, and destroy or alter what is undesired. Aggression results in belief: that there is discontinuity between what is being affected by action, the action itself, and the actor (when, in fact, all are co-dependently originating and equally integrated in their termination). Belief results in numerous attachments: when a person invests effort into something, they believe they possess it; a person greatly attaches to their beliefs of ownership, and beliefs of beliefs.
But Krishna said that anything which is taken up may be let go of, and instructed in a means of "sacrifice:" Faith in reality (the first premise of Krishna's logic is "reality") permits a person to achieve non-desire (Ni-Vana) by giving up what is attached to.
Gotama expanded upon this understanding by teaching a method by which attachment to reality is also sacrificed. Gotama instructed that our understanding of reality is based upon what we see, hear, taste, smell, touch and the way that these senses are interpreted through thought. Since our capacity to sense and understand a reality which we are a part of is necessarily biased, we must sacrifice our understanding of reality. This sacrifice meant giving up reductive and inductive reasoning for inferential reasoning.
This process of inferential reasoning required testing not only our senses, not only our thoughts, but also our very identity. This permitted not only Ni-Vana, but that which lay beyond when nivana was given up: self-sacrifice (the identity sacrifice) was the means by which the very constraints of binary logic might be broken, and freedom obtained. Freedom is both the means and the end of perfecting our humanity into something even Indra and Brahma would envy.
Indeed, when it is understood that we can only understand our world to within degrees of certainty, and this probability is less-than-perfectly-certain, doubt and uncertainty can be transformed from a handicap to a powerful tool. The nature of reality is far more complex than we can understand, but it is unnecessary to understand reality perfectly.
Relevance is therefore the test by which beliefs are sacrificed. Both Krishna and Gotama agree, it is unnecessary to give up belief in gods, it is equally unnecessary to hold belief in gods. It is foolish to take responsibility for the full consequences of our actions when the greater part of our existence is beyond our control - and equally foolish to not take responsibility for what we can control. Ritual, habit, religion - these are sometimes necessary expressions of our humanity, and if we are to let go of our humanity to become something greater, we must first take them up.
There are no solid grounds for reasoning, there is only falling through air - with no up, no down, no direction at all. For both Gotama and Krishna taught a sacrifice of the directions. There is no beginning, no ending. There is no nothing, nor is there something. Such freedom can be very disconcerting if you have not grown strong enough, mind and body. A bird cannot fly as soon as it is hatched, even though its destiny and nature is to live in the air. Why should a human being be able to thrive in freedom merely upon being born - even though it is our destiny and nature to be free?
A human baby eats no food, nor is able to - it must grow to eat food. It is reasonable to expect we should grow in other ways as well. Yoga is a practice of growing. We grow beyond both needing gods, and not needing gods. We grow beyond our selves, beyond our humanity.