Of course many people who do believe in God seem happy enough. Each to his own.
The point is that happiness and morality do not seem to have very much to do with belief in God or with religion in general.
You want to be happy? Do good work. Help others. Be of service. Live small and stay within your budget. Arrive a little early, stay a little late, and do more than your fair share. Do esteemable things, and you will have self-esteem. Build for time and distance, and delay gratification. Give without expectation of getting. Find the invisible people that serve, and heap a little recognition and praise on them. Live a life of square corners. Routinely walk through field and forest to get resized. Pay attention.
That's all there is to it. It's really that simple. It's not about more money, or the right spouse, or a bigger house, or a faster car. It's certainly not about where you pray. If your door to happiness or morality is that small and pinched, you may never get through to the other side.