I'm sorry for your husband's unyielding attitude; even if he has no regard for God or the church, he still should be willing to go for the sake of his family. A parent may not be particularly interested in soccer or basketball, but that shouldn't keep them from attending their children's games. Perhaps you (or your children) can persuade him to reconsider.
The best approach is for you (and your husband) to be as positive as possible with your children, encouraging them and letting them know you are proud they've been selected to be in the Christmas play. At the same time, remind them gently that their father chooses not to go to church, and tell them honestly that he won't be going on this occasion either.
Don't argue about it in front of them, however, and don't go into the reasons why your husband dislikes church. In time, they'll probably want to explore this, but right now they're too young, and you need to do all you can to encourage respect for their father. The Bible tells children to "Honor your father and your mother, as the Lord your God has commanded you" (Deuteronomy 5:16).
The most important thing you can do, however, is to pray for your husband, and ask God to help you be an example to him of Christ's love and joy. Plan special activities for your family also that will point to the true meaning of Christmas: the coming of Jesus Christ into the world for our salvation.