Background 2: I intend to write a much bigger piece on this - taking months, but as you asked, here is an half-baked argument.

Part I
There was one very important lesson that I took from physical chemistry (please apologise if I've forgotten some of the technical details), and it has to do we the models that we have of reality:
It turns out that we know "everything" about physical chemistry (everything in comparison to say, biology, economics where we know little) (interesting that, though we know everything, there is still the uncertainty principle), anyway, my point is another: From ab initio methods, to semi-empirical methods to newtonian mechanics -  this is a scale where we very easily loose our ability to predict how systems work. Ab initio is better, semi-empirical methods less and newtonian mechanics worse....

What is interesting is that newtonian models are, (compared to economic, biological, ...) still grounded one a detailed and profound knowledge of reality.

Our scientific knowledge in "soft sciences" is weaker than newtonian mechanics is for physical chemistry.

That takes me to my first argument: What we know in psychology, biology, economics is much less than we think we know (as an aside, I think your theoretical background might be disadvantageous here: you are in a cognitive world where too much is known. Soft sciences have much bigger amounts of uncertainty and error).

Part II

I am able to find, in the majority of papers that I've carefully read in my area, errors (most of my work last week, was precisely finding an error on a paper). There are people in my area that say that they've never found a completely sound paper. I can point you errors (mathematical) in 80% the papers that I know in the area of malaria resistance modeling. I doubt I can do any better. Population genetics is an extremely complex issue when put to practice. There are much more complex things than population genetics.

My second argument is: Our human cognitive ability might be not enough to understand the universe: Maybe we will never understand the fundamental parameters driving the spread of malaria (although we will delude ourselves that we do). Or we maybe never understand how our brain works. We might not be able to understand, by our own limitations, how the universe works

Part III

We need certainty, we abhor uncertainty. There is a world out there and we need to understand it in order to cope with our fears and doubts. If no rational explanation exists then religion is better than uncertainty. It gives us comfort. We need it, psychologically.
It also makes us like authoritarian models of science (aka, "mathematical proof" that malaria can be eradicated in certain way), they give us comfort. We prefer to read a "definitive proof" then an argument saying "There are lots of doubts".

Part IV

This is not an argument in favor (or against) "higher powers" and a spiritual world. It is just trying to give an evolutionary explanation to the existence of religion.
This is not an argument against science. Just because we might not be able to understand the universe, that doesn't mean a god is needed. It might just be our inability to comprehend complex things.

Part V

A suggestion: you might have to live with your doubts and anxieties about this forever. Keep it cool: maybe there is an afterlife, maybe it is just your brain making things (maybe there is a common cognitve/emotional human response to death as they say), who knows? The best answer for this: a pint at the pub.