This one bothers me. I live on a military base and the church is used for Catholic as well as protestant services. As a result, we have a small chapel at the back in another room for the Eucharist.
We can not have any statues on display or the protestants protest.

Also, no crucifix is allowed to be displayed if it has the body of Christ hanging from it.
As a result we have to move these objects into church before mass and remove them afterwards. However, do you know what is always present in church? Thats right, the old red white and blue 24-7. Christ or depictions of him have to go into a closet, but thank God for the flag!
I must admit that I don’t think the flag belongs behind the alter, but I don’t think it is explicitly wrong either. What is distressing is that the flag is the largest thing in the church and is the most visible. It is mounted on the wall behind the altar and is the highest thing in the church. There is no cross, no depiction of Christ nor anything religious higher. The flag is the highest thing in the church and this is what bothers me.
Maybe I am jaded bceaue I remember reading about Nazi Germany and how the Nazi’s slowly took control of the churches in Germany. I can’t cite references off the top of my head, but I recall the first thing they did was put the Nazi flag in the church. Then it had to be up on the wall in church and eventually the flag came to replace the crucifix mounted onto the wall behind the altar. As I recall it took a few years for the change to come about, but that is essentially what happenned. Anyone with greater knowledge for or against my dilapidated memory feel free to expound/correct…
Now I am not saying we are socialists or anything. What I am saying is that old glory has a place in church, I just don’t want it to be anywhere near or above the Real Presence. Everything in it’s place, I think.
For what it is worth, I am active duty military and very proud of my flag and what it means to me.