Ignoring the argument from consequences just supposing you heard an argument that made you change your mind and you lost your belief in God. Would you then think it ok to steal, murder and rape because nothing matters?
Ignoring the argument from consequences, I agree with the basic point that regardless of belief or lack of it, people still have a personal morality. So while I agree that individuals and societies decide what matters to them, regardless of whether they have a belief in a higher power or not, I don't think the psychology of personal morality is clear cut.
https://www.forbes.com/sites/nicolefisher/2019/03/29/science-says-religion-is-good-for-your-health/?sh=755f618c3a12From the article, which links to research, it seems there is research to indicate that belief in a higher power does have an influence on thoughts and behaviour - and that influence can be good and bad. The extent to which that influence operates in a loop based on the person's nature / nurture is yet to be ascertained and probably varies from person to person.
But the article shows that positive thoughts and outcomes can be linked to belief e.g. effect on mental health, which is linked to physical health outcomes.
There are lots of behaviours that can be affected before you get to stealing, murder and rape - e.g. from the article "Words that are often associated with religious beliefs include connectedness, hope, optimism, trust and purpose. All of which have been shown to boost mental health. Compassion, forgiveness and gratefulness are also qualities that are strongly associated with individuals who are spiritual and religious. Practicing these qualities is thought to be associated with decreased stress and increased resiliency.". I would say that this has been my personal experience if I was to compare with my former atheist self.
Of course it's possible my thoughts may have changed anyway over time, while still being an atheist but I personally don't think so - since I remember specific instances of a thought about a higher power in the context of gratefulness, mercy and compassion expressed in Islam that changed my personal perspective and /or approach to an interaction with someone else. And if I switch to an atheist outlook, my perception is that my thoughts change and losing that component of caring how I am judged by that higher power does not seem to induce a feeling that I would consider beneficial.
Of course there are lots of examples of religious belief leading to behaviour that is the opposite of compassion, forgiveness and gratefulness so it's not possible to generalise that religious belief only leads to positive thoughts.
And of course, none of this tells you whether a higher power really exists. But since the thread is about Searching for God rather than offering proof of the existence of a higher power, presumably the point is that the process of searching can have an influence on people's thoughts and behaviours.