I'll never understand people who, when given the infinite moral and ontological agency that would be afforded to them by atheism, would rather do something as infantile as saying "fuck it, I should just die then". You can literally pursue the things you find meaningful, and ascribe meaning wherever you like, and decide what is right and what is wrong using reason or logic (or whatever you like). People can try to tell you how to live your life, and if you want to participate in society you generally have to make compromises and optimize for things in an altruistic way, but if you have a better idea you can always ignore them and go do your own thing without feeling bad about it (or better yet, convince them why your idea is better). At the same time, as with most things, there is an obvious notion of doing it "well" and doing it "badly", in that people would tend to agree that just instantly killing oneself isn't an ideal existence, regardless of whether there is any kind of afterlife or some kind of objective morality that transcends time and culture.
If your religious beliefs were somehow proven to be invalid, I guarantee you wouldn't just kill yourself, as you claim. You'd ascribe meaning however you can, and live your best life, as you always have.
If you are gay or otherwise something that was (previously) on the fringe of accepted culture, it becomes super obvious from a young age that people who try to tell you how to live your life are full of crap. I figured this out at the young age of 9. What shocked me then and continues to shock me now, though, is the cowardice and ignorance of people like you who, faced again with infinite moral and ontological agency, are afraid, and would rather die than have to come up with meaning and purpose themselves. What a boring, privileged, and childish take. People like this are either chronically unimaginative or have simply never experienced any adversity of any kind.
Still, some will press on and say, OK, well why is it that organized religions around the world tend to be somewhat similar despite tremendous geographic boundaries throughout history -- isn't it significant that all these different people and cultures came up with very roughly the same set of ideas and moral values? Of course it's significant! The power of the placebo effect is well documented and religion, if you think about it, is the ultimate placebo, and we've had hundreds of thousands of years to evolve the optimal set of religious values that produce the most dopamine while being the best at placating and controlling the general populace with promises of an afterlife and judgement for wrongdoing (where wrongdoing is anything that threatens the status quo). The best part is even if you agree with one particular religion, you have to acknowledge that yes, other religions seem to provide the same existential, spiritual, and psychological relief across the board (hence the millions of practitioners), and seem to organize society in a way that is pliable and easy to be led by a centralized authority (which historically is a good predictor for the success of things like empires, etc). So is it really surprising that after running hundreds of thousands of years of randomized trials to find the most effective religion with the best placebo effect, we've arrived at a select few that placate most people at least until they examine their convictions more closely and are properly educated? Knowing this, you could just as easily ascribe meaning yourself to get similar effects, so why go to the trouble of believing in something you know deep down to be false? You could get all these same effects, minus the cognitive dissonance of doubt, by simply taking charge of your existence and ascribing meaning to things you care about.
On the flip side, how are people so OK with the idea of an afterlife? When surveyed, most people say they would not be OK with living forever, yet we are all supposed to look forward to an afterlife where we do in fact live forever? What if heaven turns out to be not to your liking, and then you are stuck there forever? Wouldn't it then be a sort of hell? Even if you like it at first, eventually we get sick of everything anyway (without the urgency created by having limited time, meaning fades regardless of what you believe), so if heaven existed, it would eventually be hell no matter who you are. To eternal life, or any kind of an afterlife, I say no thank you unless I still have the option to off myself when I feel like being done. What right does some God have to imprison me in some eternal "ideal" afterlife and never allow me to just end, if I want to? What if the people he saves are actually super annoying sycophants and I'm stuck listening to them blather for all of eternity?
But, the religious person will say, "how can you believe things just end!! That's horrifying!!". Again this is such an infantile take. Maybe to an 8 year old this is horrifying, but if you think about it, it's not horrifying at all. Pain is scary, sure, and we don't like to imagine those we care about having to live on without us, but if you're simply afraid of the state of "not existing", full stop, you're being silly -- you wouldn't be there to experience whatever it is you're worried about anyway, because you wouldn't exist, you wouldn't be able to experience, so it couldn't be a negative or a positive experience! Sounds incredibly relaxing to me, knowing that eventually I don't have to exist anymore. If anything, it is much, much scarier to believe that perception or consciousness continues after death in some way, especially if they used ugly drapes and you're stuck with that for eternity.