Almost all the descriptions of Karma and the like require some kind of supernatural agent, basically a god, to oversee it as well as a continuing soul to receive the karma, destiny, etc. The versions that do not require a god and/or a soul are so vague that they are not at all useful for explaining things or for consoling yourself. The details of one’s particular concepts may make a difference in whether or not he can reconcile them with his disbelief in a god.
The ideas about karma, things happening for a reason, destiny, and an order to the universe, etc. come from the same need that the belief in a god used to take care of. The idea of living in a completely non-conscious universe that has no built-in system of fairness, that only follows patterns we call physical laws but not moral laws, that not only does not care about us but also can not even know that we exist, is a very scary thing to many people. So when their belief in a parent like god crashes, they may still be attracted to the comforting reassurance that there is some kind of order or justice to things; and that we can have some kind of input, however small, to influence the things that happen to us, by virtue of our moral behavior.
So what exactly is karma, and how does it work?
In its new age form, it’s referred to as the ‘law of attraction’, which is an equally preposterous pseudoscience.
A plausible explanation may come from in thinking of karma as just a guide, a way to label things, to navigating the possibilities in quantum spacetime. Whenever we make a choice, that choice affects our future choices. So, when you bring other living beings, who react to our choices, into the situation then our choices start affecting the future choices of others. Thus, in a system of individual beings making choices, a feedback loop is established. It’s kinda like my reactions and choices feeding off of your reactions and choices which feed off of my reactions and choices, and so on so forth - setting a chain of events. If your life, looked at as a whole, is nothing but destructive interactions feeding back on themselves, then – to put it curtly - you being a jerk to other people will result in people being a jerk to you. On the contrary, if you are nice to people and surround yourself with people who react positively to your choices, then you will create positive feedback which means more ‘good’ things will happen to you and happen around you. It can be broadly understood by the tenet ‘as you sow, so shall you reap’, and is manifested in various theories and principles as well: like game theory and all. Truly, the most basic of all the things are often made the most complicated!
Here’s a new insight: Modern Physics can map the concept of karma onto Hugh Everett’s many worlds interpretation of quantum mechanics. The branches that your reality takes as you move through time are dictated by what is possible - based on all your existing choices. Ergo, if you chose to ill-treat an acquaintance years ago, there are very few possible branches for your timeline where good things will come to you from that person. If you run into each other again, that person is more likely to harbor resentment and treat you coldly. On the other hand, if there are a large number of people in your life who you have treated well, then not only will your timeline easily be able to branch into realities where the people you have done good things for return the favor, but people you don’t know who have seen or heard of your deeds can be inspired as well, which may come back to you if you meet them or their choices and deeds can affect you somehow.
And not to forget the danger of 'believing' in karma which can come to the fatalism of saying “It’s too late now; everything is already determined by my past actions.”
The bottom line is that there is no reason to think that the concept of karma is tied to an intelligent being or purpose. It can be a systematic function of our reality, emerging from the rules that autonomous beings with free will have to follow in order to live. Karma is probability and statistics, not woo. Unfortunately, it has been woo-ed to hell and back by everyone who has ever tried to describe or popularize it. Hopefully, that will change.


