We have to trust others just to carry on with our goals in life, we have no real choice in the matter. It's part of the social contract we assume as social and civilized beings. The risk we take in driving, running, cycling on roads is mitigated with laws, but even that doesn't remove the risk. We can't let fear totally control our decisions. I've had quite a few cycling friends killed and injured by drunk and careless drivers over the years, but we cyclists are aware there's a risk. There are things cyclists can do to help increase safety on the road.
But contrast this with trusting a God. How does that work?
The same way. "God" is the 'source, sustenance, and purpose of all that is'. And is therefor a mystery to us. The great mystery of (all/our) existence. And we need to be able to trust in this mystery to continue to function within it. Yet we don't know that we can trust existence not to harm us. Just like with the other drivers on the road. But still, we hope that we will be safe, and we choose to trust in that hope, and to act on that trust. Because the alternative is unacceptable. The alternative is fear and stagnation.
But a lot of people have difficulty trusting in such an unknown as the 'great existential mystery'. So they personify it, feeling that somehow they can relate to it better, and interact with it in some way. Whole religions spring up with sets of rules and rituals that help people feel that they are able to trust in and interact with this great existential mystery. Others reject religion and turn to "scientism"; imagining that somehow science and empirical reasoning will provide them with the ability to control their own existential fate.
But in the end we're all still living in the dark. And it's all still about finding and choosing the object and methods of our faith. "Belief" has nothing to do with it. Belief is just our egos telling us we're right when we really have no way of knowing that.
You trust your child won't have serious health problems, but alas your three year old is diagnosed with Leukemia. But you trust in God that the doctors will implement painful treatments that will save your baby, but alas after 2 years the child dies. So an all-powerful god that supposedly can save the child and knows of your trust just decides to ignore you, and kill a child?
Yes. And people do lose hope. But it's a horrible way to live. So most people find some way to hope and trust, again. The alternative is unacceptable.
As we see above regardless of how we fallible mortal extend trust, it is not always reliable or based on reality.
But the alternative is unacceptable.
Your scenario here admits you don't know if a God exists, and you are gambling with the hope that it does. You're relying on your ability to create and illusion and work hard to maintain the deception to the self that it's real and helps. But despite this work you still know you're on your own, whether it's the illusion or having to make your own decisions in life to cope with whatever challenges come your way.
These are not mutually exclusive conditions. Everyone is having to make their own decisions and then hope and trust that they're the right decisions relative to the great existential mystery that we're living. Theism helps a whole lot of people do that. So does religion. So does science. So does logic, and reason, and intuition. So does engaging in the creative arts. So does philosophical discussion and debate. These are all tools that we humans use to try and deal with our own profound ignorance. And you are one of us, too. You are no different. You are just as 'unknowing' as the rest of us.
What you describe is people who cannot trust themselves, nor have the confidence to navigate life with a realistic understanding of how things are.
We live in a profound state of ignorance. We have no idea why we are here, or to what end. Or what will happen to us or to those we care about at any given moment. So yes, we need to find things to hope in, and ways to trust in that hope, just so we can muster the courage to take action and see what comes of it.