How incredibly sad for your child. It's silly to argue over food.
He's hungry, it's a parents job to provide food. Feed the child. Allow him to eat when he's hungry.
Most kids need to eat a meal, have a snack, eat a meal, have a snack, eat a meal, and have a snack before bed.
They should be allowed to eat something every 3-4 hours regardless of when you eat dinner and how much of it they ate. That's an entirely different meal. That's like saying "You didn't eat your grits at breakfast so there's no way you're hungry at dinner, you can't eat anything right now".
Kids metabolism burns food differently than an adults. They also have a smaller stomach/food track so they get hungry more often.
Even if he eats a full dinner he should get a snack before bed, he's going to be without food for 8 or more hours and if he's hungry he's going to wake up in the middle of the night.
Now, my honest opinion, my own 2 cents worth.
Your son wants cereal, so he goes to get it, mom and dad argue and fight and more. So he just goes and gets what he wanted to begin with, food that he likes. He wins.
If you were my neighbor and I knew you were denying your child food when they were honestly hungry I'd call social services on you. If I was your mother and knew you were denying my grand child food when they were hungry I'd go to court and take them away.
I truly thought you and your husband were teenagers/very very young parents.
No parenting classes in the world will make any difference because of this:
If your goal is to make your child conform to your rules and by GOD they will obey you when you say anything then parenting classes won't help.
Parents are not supposed to make rules like that. If he'd have wanted a candy bar or a piece of cake it would have been different. Cereal is fortified with vitamins and minerals. It's not unhealthy. Milk is good for kids. The meal he picked wasn't a bad meal.
Tonight I had a little bit of pizza then when I came home and got settled down I ate half a tub of Cheddar Pasta Salad from Walmart. I love that stuff. Was it a great meal? Healthy? I've had worse meals as far as nutrition goes. But if someone came in and told me I was not allowed to eat when I was hungry they'd have had a fight on their hands. It wasn't full from pizza and I wanted the pasta salad. No big deal.
Please consider getting some counseling so you and your husband can comes to terms with what is expected at your house. Fighting over food and meals only leads to fat children and dead children who starved themselves.
You are teaching your child that food is power and that he can control everyone and everything in his life with it. You're not teaching him good things in this instance.
Please read through the answers again, many of us have said the same things. When a child is "forced" to eat food they don't want or don't like they develop issues with food that will haunt them the rest of their lives.