I have preached at various times about the proper behavior in church, seemingly to no effect. I have not always been consistent about it myself. Maintaining silence and prayer in church is something that we need to work at together. Father Zuhlsdorf has posted some great thoughts on this topic, from which I quote extensively here – you can read the whole thing on his blog.
Most of our churches are consecrated. They are holy places. Their walls are anointed with chrism. They have been given a name. They are sacred places. Within their walls we participate in the most sacred act we little humans can be privileged to witness, which God Himself gave us to renew, before which the angels themselves bow and worship: the Holy Mass which is the Sacrifice of the Cross.
In Washington, DC you find the Tomb of the Unknown Soldier. An elite corps, the Old Guard, maintain watch at the Tomb. They preserve the decorum of the place. They correct people who do not maintain proper decorum.
Here is a video of one of the sentinels silencing people who are talking loudly and laughing near the Tomb of the Unknown Soldier, crossing over the chains and boundaries, remaining seated when they can stand.
Remember this video… when you yuk-it-up or shoot-the-breeze in your parish church [....] If this level of decorum is expected at an outdoor secular tomb, how much more should we expect decorum within the hallowed walls of the place where Mass is offered?
I remember stumbling upon the Tomb of the Unknown Soldier when I was in Portugal. It was rather deep within an ancient monastery that was pretty much in the middle of nowhere – not where one might expect to find it, such as in a big city like Lisbon. I had no idea it was where it was and was quite surprised to find it. The place was not very frequented by tourists, at least not at the time I was there. I don’t recall any signage (for the tomb) on the highway. It was just there. And so was an honor guard – around the clock I think – who took their job very seriously. Two soldiers guarding the tomb, and another maintaining order. I didn’t even dare take a photograph of that area of the monastery.
See Fr. Zuhlsdorf’s whole post here.