The first and most important is the belief in Christmas among the soldiers of the three countries. We see that some of them are saddened by the reality that they will not spend Christmas with their loved ones. From this we can conclude that they all share the same relative religion and that they cannot be different from each other from what they thought or what they had learned before. In the name of the holiday spirit, they were able to put aside their differences and celebrate together without the bad intentions that we see in war. They also all share a mass led by the Scottish deacon who was on the battlefield and all seemed to follow together. I think that night the soldiers realized or became clear that instead of seeing their worst enemy in front of them, they saw another comrade who was doing exactly the same thing as them, that is- say survive as best they could. They learned that they were in the same hell and that they had compassion for each other. That's why later in the movie everyone was hesitant to kill another soldier, they had seen him and befriended him and when you become someone's friend it's harder to pull the trigger and kill him. Another religious aspect was when they all agreed to cease fire once again in order to gather and bury their fallen brothers. While digging the graves and going through the belongings of a dead soldier, we saw that some wore a belt with a religious saying. Then I remember a soldier placing an object in a dead man's mouth. This can possibly show that it could be some kind of tradition and it could be followed by a religious aspect. Towards the end of the film, when the superiors discover the soldiers' agreement, and even the bishop discovers it and comes to scold the deacon, I think it was very hypocritical. Here is a man of faith, who is supposed to preach about the preservation of human lives and preach about the death of the wicked.