Religion offers nothing positive to the species, and theism is a truly horrific thing. But that aside, let's disprove all gods and be done with it once and for all.
This is often thought of as impossible, but not if we use the modern definition of a god, the ones used by Christians and Muslims. This particular definition makes said god impossible to exist because of one simple fact, it demands infinite regression.
Religion as a whole is nothing more than fanciful stories, rituals, and essentially clubs. Nothing bad is inherent in these, until dogma is added, theism requires dogma.
Deism is often mistaken to theism, but it is not. Deism is theism without dogma, a very agnostic view in all reality, and technically deists are atheists.
The reason is that theism forces the deities to be human and necessary, this makes their gods impossible. For if everything requires a creator, then so does the creator require a creator.
This rather lame argument used by theists was started by the very primitive brain of pre-Stone Age humans. They were unable to comprehend the chemical reactions that occur all the time, much less the atomic reactions and forces involved.
When I was growing up I had studied Chaos Theory, at the time that's what it was called. After some discoveries Chaos Theory vanished and was replaced by a series of laws, mathematical formulas used to predict natural behaviors of reality.
I still call it Chaos Theory in casual discussion, and almost no layperson actually understands it. To my surprise it's a fundamental part of quantum mechanics now.
This simple yet profound change in knowledge illustrates how religion was born. I could start a cult by manipulating the people who know nothing of chaos as easily as one who manipulated those who did not understand the forces of nature.
The difference between me and a preacher is that I have morals and empathy. To manipulate the gullible fools in such a way would only be self destructive, for unless those fools become intelligent, we will die and the more fools there are the more horrible our deaths will be.
Preachers need to consider this point thoroughly, for it is with the tools created by our intelligence that we can have any possibility of avoiding this horrific fate. You need to become more self serving to avoid being self destructive.
The point often forgotten by religious people is that without a god we must protect the planet and our own species in order to survive, with a god you have no reason to worry about being good to anything. With a life after death you have no reason to worry about the life before it, without a life after death you must work to delay the inevitable annihilation.
This requires we stop being so selfish as to believe we are the "chosen" or some special species outside the laws of the wild and nature. We must accept our humble place as animals, dependent on this world, on this universe that so wants to destroy us, for our very existence.
We must be honest enough to admit that there is nothing out there that will save us from ourselves, we must do it all, as we always have, without help from some superior being. We must embrace our own existence to continue existing.