In my experience, that’s to say this is just my opinion, people have a psychological need for fulfillment in service, fellowship, and worship (admiration (or awe) + gratitude) as well as a need for a solid approach to ethical behavior.
Theism supplies all this but does require an ability to not reconcile belief to reality. For those that can do this I think it’s the best way for them to proceed.
Atheism doesn’t supply anything as it’s merely a lack of belief therefore the individual is left to cobble together a personal system that in my observation typically ends up leaving out worship in part or in whole and a shallow approach to ethical behavior such as rational egoism (LOL, people can rationalize anything, Hitler was rational) or altruism (LOL, just ignore human nature and self-interest), etc..
Syntheism is an attempt to supply awe to the individual atheist with some kind of back to nature “spirituality” (new age crap).
Symtheism supplies all that theism does with the added “benefit” of being able to reconcile belief to reality. There is plenty of wondrous mystery and awe inspiring power with regard to the laws of physics to motivate as much admiration and gratitude as anything imaginable. The approach to ethics is solidly founded on morality based on hundreds of thousands of generations of experimental data which is as objective as it gets with respect to morality. As Dr. Jordan Peterson might say behavior that is ethical is that behavior that works for me, my family, my community, my nation, and humanity for today, tomorrow, next week, next year, next decade and next century. This is what Stefan Molyneux might call universally preferred behaviors (UPBs). The Judeo/Christian tradition starts with UPBs experimentally derived over thousands of generations, condenses them into an admittedly overly rigid Law, which moral principles are extracted from forming a flexible yet solid approach to ethical behavior for people immersed in western culture. Also worth noting is that one can engage in mainstream Christianity as a Proto-Christian or Symbolic Christian; obviously not a Catholic or denomination that requires some oath or creed, but the more progressive and inclusive denominations that came out of the Restoration movement such as Disciples of Christ (of which I’m a member) or a nondenominational church are certainly options for the Proto or Symbolic Christian.