Imagine if all life on Earth had no purpose and was not created by some superior intelligence.  All life would be no more important in the grand scheme of things than any other life- humans, animals, plants, bacteria.  We're all here due to a chance forming of proteins creating more complex molecules over billions of years.  Where is the story in that?  If all life is equal in terms of importance, then really it doesn't matter if we get hit by an asteroid or half of humanity is wiped out or even if all of humanity is destroyed.  If the Earth was destroyed right now, it wouldn't matter, no one would care, no higher being would feel sorry or try to do anything to stop the event, because the whole time we were a bunch of randomly evolved organisms that happened to live on our rock, which happened to form through some unlikely astral ballet that gave us the perfect balance of heat and life sustaining elements.  And how can you feel warm and fuzzy from that?  You can feel awe, but only at the sheer vastness and emptiness of the universe.  And that sucks.  That doesn't feel good.  It makes humanity a tiny curiosity. 

 Look at how humanity functions.  We're smelly, hairy, sex addicted, and biologically similar to apes.  That doesn't sound like something to be proud of.  Humans are just like animals, just as able to live, procreate and die without possessing a soul?  That doesn't feel good.  We should be better than animals.  We should transcend our existence, become spiritual beings in another dimension, where we can meet some supremely powerful and intelligent creator and learn all the secrets of the universe and be reunited with our loved ones.  Because if none of that happened, if we just died, it would suck.  And who wants life to suck?

Now let's say you didn't believe life sucked.  Look at all the random causes of death from natural disasters to car crashes.  Look at all the crime in the world, the unbalanced treatment of people, the impoverished and the diseased, those who are born with birth defects and mental disabilities through no choice of their own.  That's not pleasant.  Sure you can go about your life unaffected by the world's problems, and you can look out for yourself and your own interests, but then your whole moral foundation is based on you and you alone (and the laws of society), so if you were to be the next Hitler, you wouldn't have any more spiritual consequence after death than anyone else, because there are no spiritual consequences.  There's no spiritual accountability, no higher being to declare what's right and what's wrong.  Entire countries could misbehave and commit horrible crimes and we'd have to actually deal with it rather than letting an otherworldy caretaker handle it.  That just sucks.

But if all religion is wrong, then look at how foolish those followers have been.  All the architecture, poems, songs, sacrifices, martyrdom, all the time spent in worship and prayer and humility and abstinence.  All the symbols and names and stories and rules and everything, all for nothing.  Sure you could accept that, but it would mean hundreds of thousands of people are wasting time doing nothing, all that effort going nowhere, with no payoff, no point, nothing.  Think of the enormous failure in terms of human progress.  And that would suck.

So, given that things suck, and I can imagine things not sucking as much, the logical conclusion is that things should not suck and there should be some alternative in which everything is good, because that's what I would like, since what I want should be reality (since I want to want my wants to be reality), so there must be some magical realm in which things do not suck.   Cogito ergo something.