It's time to move out, even if you have to move to a shelter for a while.
These people need to understand that you are not their responsibility nor are you theirs to manage. I am all for grandparents bringing different aspects of life to our kids but when they make it a rule for you being there, that's wrong.
Now, if you were bringing in drugs or drinking all night then I'd say they might have a basis for telling you that you need God, okay? I'll give them that.
But ordering you to produce your children every Sunday morning for church or pay more rent, that's entirely stupid and insulting and rude and enough to push me right out and I "DO" go to church.
Go, today and sit down with your parents. Let them know what's going on. Ask them if there is anything they can contribute to your housing and living arrangements.
Can you live on a nearby base? Don't they have social workers that help soldier families?
As an out of country serviceman's wife? Is he overseas? In a war zone? Isn't he on a base where you could go? And take the kids?
Your older kiddo could stay with your parents and finish out this school year then join you guys on the base where your husband is. A friend of mine has an adult daughter who met a man from Finland. She went over to visit him and fell in love with the country and him, she married him.
Her son was in school and very happy at the time. Since she was going to marry this man she hadn't known even a full year she did want her son to be protected just in case. So she left him with her mom, his grandmother. Grandma was given guardianship by mom, they went to court for this so it was on record at the courthouse, and this meant that grandma could enroll the kiddo in school, decide about medical care, had full authority to act in his behalf as a parent would. No one had to call overseas and speak to the mom, grandma has full rights to make all his decisions. The boy and grandma would fly to Finland to visit a couple of times per year and this way he got to know his step-dad and make Finnish friends.
When the daughter had been married a couple of years and her son was about to enter high school he decided he was ready to move to Finland. He went and is in college now. Fully happy living in Finland and expects to live there forever.
Point is, there are options that work out in all sorts of ways. You don't have to live under this man's thumb and obey him like he's important or something.