If you don’t believe in a god, but your parents do, that can be a problem.
If you’re a young person who is dependent upon your parents for food and shelter, and your parents are strongly religious, you could be causing yourself a lot of problems if you announce your atheism to them.
There have been many cases of young people who have been kicked out of their homes or even physically harmed because they no longer believe in a god. We expect our parents to act rationally. But parents are human, and humans don’t always act the way they should. This is especially true if they’re under the influence of religious ideas that stress obedience, following rules and authority, over empathy, identifying with the feelings of others.
It’s important to be true to your principles. But at a time when you’re vulnerable and are dependent upon others for your physical well-being, it’s even more important that you keep your system of support intact.
Once you are independent, you’ll be much more free to voice your views about god(s). Until then, unfortunately, it is a better idea to keep your ideas, though true to yourself, to yourself.